Intraluminal radiation treatment system

ABSTRACT

A transfer device and catheter assembly for the delivery of treatment elements to a selected location within the intraluminal passageways of a patient as part of an intraluminal radiation system. The transfer device includes a gate member that permits the treatment elements to have the transfer device only if the catheter is attached thereto. A pressure indicator provides a visual indication of the fluid pressure within the transfer device, and provides for a release of the fluid if the pressure exceeds a predetermined pressure. The catheter also includes detents to secure it to the transfer device and which must be manually activated to remove the catheter from the transfer device. The transfer device includes circuiting that determines whether the treating elements reside within the transfer device based upon the reflectivity of the treating elements. A method for determining whether treating elements reside in the catheter is also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a division of application Ser. No. 08/936,058, filed Sep. 23,1997, now U.S. Pat. No. 6,013,020.

This application claims the benefits of provisional applications Ser.No. 60/026,566, filed Sep. 23, 1996; Ser. No. 60/041,090, filed Mar. 14,1997; and Ser. No. 60/052,708, filed Jul. 16, 1997.

The present invention relates generally to an intraluminal radiationsystem for the delivery of treatment elements by way of a catheter to aselected location within the intraluminal passageways of a patient. Moreparticularly, the present invention relates to an improved transferdevice for handling the treating elements and delivering them to thecatheter and an improved catheter assembly.

BACKGROUND OF THE INVENTION

Since the late 1970's balloon angioplasty techniques have become widelyused for opening blockages in coronary arteries. Briefly, theenlargement of the artery is achieved by advancing a balloon catheterinto a narrowed portion of the artery and inflating the balloon toexpand the diameter of the artery, thus opening the artery for greaterblood flow. Atherectomy techniques, in which blockages are removed orreduced in size, have also been used to the same end.

While balloon angioplasty has proved an effective way of opening thecoronary arteries, in a significant number of cases the arteries willnarrow again at the location where the balloon was expanded, suchnarrowing being termed restenosis. Restenosis is believed to be causedby formation of scar tissue at the site of the angioplasty that resultsfrom the injury to the artery caused by the inflation of the balloon.

More recently, intraluminal radiation has been used after angioplasty oratherectomy to treat the affected area of the artery to inhibit cellproliferation and wound healing response and, consequently, help toprevent restenosis. Methods and apparatus for such intraluminalradiation treatment are disclosed in the co-pending application, serialNo. 08/628,231, filed Apr. 4, 1996, which is incorporated herein byreference. This application generally discloses an apparatus comprisinga catheter, which is inserted intraluminally into the patient andadvanced to the site of the area to be treated, and a transfer devicefor facilitating either the hydraulic or pneumatic advancement andretrieval of individual radioactive treating elements or “seeds” alongthe catheter to and from the treatment site.

As with any device inserted into the vascular system, it must havesufficient integrity to insure that no pieces or elements are separatedfrom or exit the device into the vascular system. This is particularlytrue for the treating elements which are moved to and from the distalend of the catheter. Additionally, because the device is intended to useradioactive treating elements, there is a heightened need for safety toprevent any unintended exposure of either the patient or the user toradioactivity.

Use of the apparatus described in the above-identified co-pendingapplication has suggested several areas where the device could beimproved to reduce the possibility of having treatment elements escapefrom the system, thus enhancing patient and user safety.

Consequently, it is the principal object of the present invention toprovide a transfer device and catheter assembly that has additionalsafeguards to protect the patient and user.

More particularly, it is an object of the present invention to provide atransfer device/catheter assembly in which the catheter cannot beinadvertently detached from the transfer device unless all the treatingelements reside within the transfer device. Similarly, it is an objectof the present invention to provide a transfer device/catheter assemblyin which none of the treating elements can exit the transfer deviceunless a catheter is connected thereto.

It is a further object to insure that the hydraulic or pneumaticpressures to which the transfer device/catheter assembly is subjectedduring the advancement and retrieval of the treating elements does notexceed a predetermined “safe” pressure.

It is an additional object to provide a method and system for detectingthe presence or absence of treating elements in the transfer device andfor providing a visual indication of such presence or absence oftreating elements.

SUMMARY OF THE INVENTION

These objects, and others that will become apparent upon reference tothe following detailed description are accomplished in one aspect by anactuator assembly for the transfer device that includes a gate memberthat is moveable between a first position that prevents treatingelements from entering the lumen of the catheter and a second positionthat permits treating elements to enter the lumen. The gate member ismoveable into the second position only if the catheter is attached tothe transfer device. The actuator assembly includes a switch memberbiased into a first position that prevents movement of the gate memberinto its second position unless the switch member is moved out of afirst position that interferes with the movement of the gate member uponthe catheter connector being received in the central opening of thetransfer device. Additionally, a trigger member that is moveable intolocking engagement with the connector when the connector is received inthe central opening is disengageable by means of a separate releasebutton.

In another aspect of the invention, a pressure indicator is providedthat includes a transparent elongated cylinder viewable by the user ofthe transfer device and housing a piston which is slidingly receivedwithin the cylinder. The cylinder includes an inlet port through whichpressurized fluid can enter, and the piston is biased so that therelative position of the piston and the cylinder provides a visualindication of the relative fluid pressure in the transfer device. Thepressure indicator can include a portion having a inside diametergreater than that portion of the cylinder in which the piston isdisposed and an outlet port in communication with the enlarged-diameterportion of the cylinder. Consequently, when the fluid pressure issufficient to move the piston into the enlarged-diameter portion of thecylinder, fluid escapes passed the piston and exits the cylinder throughthe exit port. Alternatively, the pressure indicator can be connectedand parallel fluid communication with a separate pressure relief valveof known construction.

In another aspect of the invention, the catheter includes a connector atits proximal end that is received in a central opening in the transferdevice. The connector includes at least one detent for securing theconnector in the central opening of the transfer device, the detenthaving to be manually actuable to release the catheter from the transferdevice.

In a further aspect of the invention, a method is provided fordetermining whether the treating elements reside in the transfer device.The method includes encapsulating the treating elements in a materialhaving a known wavelength/reflection ratios; shining to lights ofdifferent wavelengths into the area in the transfer device where thetreating elements normally reside before and after being introduced intothe catheter; measuring the reflectivety of the two lights as reflectedoff the area in the transfer device; determining thewavelength/reflection ratios of the reflected light; comparing themeasured wavelength/reflection ratios with the knownwavelength/reflection ratios; and indicating whether the measured ratiosare substantially the same as the known ratios.

A system for accomplishing the method described above is another aspectof the invention and includes a power source; a first light sourceoptically connected to the targeted location in the transfer device andthat emits a light having a first wavelength; a second light sourceoptically connected to the targeted location that emits light having asecond wavelength; a photosensor optically connected to the targetedlocation that measures the light reflected off the targeted location andcreating a signal corresponding thereto; a window detector fordetermining whether the signal created by photosensor is within apredetermined band corresponding to a signal which would be created bylight of first and second wavelengths being reflected off the element;and an indicator light that is activated if the signal created by thephotosensor is within the predetermined band.

DRAWINGS

FIG. 1 is a schematic drawing of intraluminal radiation systemcomprising a transfer device, a delivery catheter, and a connector forconnecting the two.

FIG. 2 is an exploded view of the transfer device of the presentinvention.

FIG. 2a is a cross-sectional view of the assembled transfer device ofFIG. 2.

FIG. 3 is a cross-sectional view of the rear housing of the transferdevice.

FIG. 4 is a bottom view of the rear housing of the transfer device.

FIG. 5 is a perspective view of the fluid control handle.

FIG. 6 is a perspective view of the fluid control switch.

FIG. 7 is a bottom view of the fluid control switch.

FIG. 8 is a cross-sectional view of the central housing of the transferdevice including the quartz sleeve for holding the radiation elements.

FIG. 9 is an enlarged sectional view of the portion of the rear housingof the transfer device that interfaces with the seed lumen of the quartzsleeve.

FIG. 10 is a plan view of the distal face of the central housing.

FIG. 11 is a plan view of the actuator switch.

FIG. 12 is a plan view of the gate.

FIG. 13 is a plan view of the proximal face of the gate housing.

FIG. 14 is a plan view of the distal face of the gate housing.

FIG. 15 is a plan view of the proximal face of the collar housing.

FIG. 16 is a plan view of the release trigger.

FIG. 17 is a plan view of the release switch.

FIG. 18 is a top view of the release switch.

FIG. 19 is a plan view of the proximal face of the front housing.

FIGS. 19a-c illustrate the interaction of the release trigger andrelease switch during the insertion of the connector into the triggerdevice.

FIG. 20 is a side view of the front housing.

FIG. 21a is a schematic drawing of an intraluminal radiation systemembodying the present invention with an alternate construction for therear housing of the transfer device.

FIG. 21b is an exploded perspective view of the rear housing/fluidcontrol switch of FIG. 21a.

FIG. 21c is a cross-sectional view of the assembled transfer device withthe alternate embodiment of the rear housing/fluid control switch ofFIG. 21b.

FIG. 22 is a top view of the rear housing of FIG. 21b.

FIG. 23 is a side view of the rear housing of FIG. 21b.

FIG. 24 is a perspective view of the fluid control switch of FIG. 21bshowing the proximal side of the switch.

FIG. 25 is a perspective view of the fluid control switch of FIG. 21bshowing the distal side of the switch.

FIG. 26 is a plan view of the fluid control switch of FIG. 21b showingthe proximal side of the switch.

FIG. 27 is a plan view of the fluid control switch of FIG. 21b showingthe distal side of the switch.

FIG. 28 is a schematic view of the intraluminal radiation treatmentsystem of the present invention.

FIG. 29A is perspective view of a further embodiment of the transferdevice of the present invention also showing a syringe attached thereto.

FIG. 29B is a perspective view similar to FIG. 29A, except for the tophalf of the housing of the transfer device is removed to show itsinterior construction.

FIG. 30 is a plan view of the housing of the transfer device of FIG.29A.

FIG. 31 is an exploded perspective view of the transfer device of FIG.29A.

FIG. 32A is a lateral cross-sectional view of the transfer device ofFIG. 29A.

FIG. 32B is a longitudinal cross-sectional view of the transfer deviceof FIG. 29A.

FIG. 32C is an enlarged cross-sectional view of one of the internalcomponents of the transfer device of FIG. 29A.

FIG. 32D is a longitudinal cross-sectional view of the transfer deviceof FIG. 29A perpendicular to the cross-sectional view shown in FIG. 32B.

FIG. 33 is a side view of the transfer device of FIG. 30.

FIGS. 35A-D show a pressure indicator/pressure relief valve, and itscomponent parts, that can be advantageously used in the transfer deviceof FIG. 29A.

FIG. 37 is a perspective view of selected interior components of thetransfer device of FIG. 29A mounted on a chassis.

FIG. 38 is a perspective view of a release switch for use in thetransfer device of FIG. 29A.

FIGS. 39A-B are the perspective views of the components for the pin gatefor use in the transfer device of FIG. 29A.

FIGS. 40A-D show the pin gate/release switch safety interlock used inthe transfer device of FIG. 29A.

FIGS. 41A-E show the catheter connector and its various subparts used inthe present invention.

FIGS. 42A-D show a catheter and its cross-section (FIG. 42D) for use inthe present invention.

FIGS. 45 is a logic diagram for a treating element verification systemadvantageously used with the transfer device of FIG. 29A.

FIGS. 46A-1, 46A-2; 46B; and 46C-1, 46C-2, 46C-3 are circuit diagramsfor performing the functions set forth in the logic diagram of FIG. 45.

FIG. 47 is a plan view of the housing of a further embodiment of thetransfer device.

FIG. 48 is a perspective view of the transfer device of FIG. 47 with thetop half of the housing removed to show interior detail.

FIG. 49 is an end view of the transfer device of FIG. 47 looking at thedistal end.

FIG. 50 is an exploded perspective view of the transfer device of FIG.47.

FIGS. 51A and B are longitudinal cross-sectional views of the transferdevice of FIG. 47.

FIG. 51C is a lateral cross-sectional view of the transfer device ofFIG. 47.

FIG. 52 is an exploded perspective view of the pressure indicator gaugeand pressure relief valve for use in conjunction with the transferdevice of FIG. 47.

FIG. 53 is a cross-sectional view of the pressure indicator gauge andpressure relief valve of FIG. 52, with the fluid flow therethrough shownschematically.

FIGS. 54A and B are perspective views of the latch body for use inconnection with the transfer device of FIG. 47.

FIG. 55 is a perspective view of the latch sear for use in conjunctionwith the transfer device of FIG. 47.

FIGS. 56A, B and C show the assembled latch mechanism, including thelatch body, latch sear, and latch button in perspective, plan, andcross-sectional views, respectively.

FIGS. 57A and B show the skirt connector for use in conjunction with thecatheter connector in perspective and cross-sectional views,respectively.

FIG. 57C is a cross-sectional view of the proximal end of the catheterconnector showing the central plug.

FIG. 58A is a plan view of a catheter for use in the present invention.

FIG. 58B is an enlarged lateral cross-sectional view of the catheter ofFIG. 58A.

FIG. 58C is an enlarged longitudinal cross-sectional view of the distalend of the catheter of FIG. 58A.

FIG. 59 is a plan view of a treatment element seed train for use in thepresent invention.

FIG. 60 is a logic diagram for the treating element verification systemfor use with the transfer device of FIG. 47.

FIGS. 61A-1, 61A-2, 61A-3; 61B; and 61C-1, 61C-2 are circuit diagramsfor performing the functions set forth in the logic diagram of FIG. 60.

FIG. 61D is a schematic diagram for a distribution board for thetreating element verification system of FIGS. 60 and 61A-C.

FIGS. 62A-C are printed circuit boards showing the mechanical outlinefor use with the treating element verification system of FIGS. 60 and61A-D.

FIG. 63A is a schematic diagram showing the electrical connectionsbetween the various parts of the treating element verification system.

FIG. 63B is a circuit diagram for an equivalent circuit to FIG. 63A.

DETAILED DESCRIPTION

Turning to the figures of the drawings, FIG. 1 illustrates anintraluminal radiation system 10 according the present inventioncomprising a transfer device, generally indicated by 12, a deliverycatheter, generally indicated by 14, and a connector, generallyindicated by 16, for securely attaching the delivery catheter 14 to thetransfer device 12. The delivery catheter 14 and connector 16 aresubstantially as described in the above-identified co-pendingapplication which has been incorporated herein by reference.

The transfer device 12 functions to house and shield a radiation sourcetrain (not shown), which may include non-radioactive marker seeds, andcontrols the direction of fluid flow for priming the transfer device 12and catheter 14 and effecting delivery and retrieval of the individualradiation elements.

The transfer device 12 is shown in exploded view in FIG. 2 and consistsof three main assemblies: rear housing and fluid control switch assembly18, central housing and actuator switch/shuttle gate assembly 20, andfront housing 22. The rear housing and fluid control switch assembliesand the central housing and actuator switch/shuttle gate assemblydisclosed herein are interchangeable with the corresponding partsdisclosed in the above-referenced co-pending application

The rear housing 18 comprises a cylindrical member 24, preferably madeof polycarbonate, that includes two axial through-lumens 26 forpositioning two screws 28 that connect the rear housing 18 to thecentral housing 20. The threads of the screws 28 can directly engage thepolycarbonate material of the central housing 80 or the internal threadsof the lumens 26 can receive helical, coiled wire inserts which will beengaged by the threads of the screws 28. Alternatively, the lumens inthe central housing 80 that receive the screws 28 can include internallythreaded metal inserts (not shown) secured therein by, e.g., ultrasonicwelding, so that the threads of the screws 28 engage the internalthreads of the metal inserts, thus providing a more durable connectionbetween the rear housing 18 and the central housing 80.

The cylindrical member 24 includes a cylindrical recess 30 for placementof a fluid control switch 44, which is discussed in greater detailbelow. The cylindrical member 24 includes two luer connectors orfittings 32, 34, preferably made of a polycarbonate and secured to thecylindrical member 24 by a UV-cure adhesive. The luer fittings 32, 34may be either partially or completely recessed within the rear housing18. Luer fitting 32 is received in recess 32 a in the cylindrical member24 and is in fluid communication with a fluid inlet channel 36 (bestseen in FIG. 3). The luer fitting 32 connects to a liquid or gas-filleddevice (not shown) that is used for hydraulic or pneumatic delivery andretrieval of the radiation source train to and from the deliverycatheter 14.

Luer fitting 34 is received in recess 34 a of the cylindrical member 24and is in fluid communication with a fluid exit channel 38 (FIG. 4). Theluer fitting 34 can optionally be connected to a fluid collection bag orreservoir (not shown). The cylindrical member 24 also includes ahydraulic return channel 40 (FIG. 4) and a seed delivery channel 42(FIG. 3). Each of the channels 36, 38, 40, and 42 communicate with thecylindrical recess 30.

A fluid control switch 44 selectively provides access between thevarious channels 36, 38, 40, and 42 to send and/or retrieve theradioactive treatment elements and marker seeds from the deliverycatheter 14. To facilitate easy manipulation of the fluid control switch44, a paddle-shaped control handle 46 is secured to the fluid controlswitch 44 and cylindrical member 24 by means of a retention screw 48that extends through a central bore in the handle 46 and switch 44 andinto a bore in the cylindrical housing 24. The bottom of the retentionscrew 48 abuts a set screw 49 to limit the movement of the screw 48 andprevent the screw 48 from being unscrewed by operation of the switch 44.A locking cap 50 closes the central bore in the handle 46. As best seenin FIG. 5, the fluid control handle 46 includes a paddle-like portion 52which may be contoured or otherwise ergonomically-shaped to provide theuser with improved control and easier manipulation of the fluid controlswitch 44.

Optionally, the head of the retention screw 48 may be notched so that alocking pin (not shown) may fit through it. Such a locking pin wouldprevent rotational movement of the retention screw 48 so thatcounterclockwise movement of the fluid control handle 46 would notloosen the screw 48. A shallow hole in the fluid control handle 46 wherethe head of the retention screw 48 rests would receive such a lockingpin.

In order to limit the degree to which the fluid control switch 44 can berotated, the bottom of the switch 44 includes a fluid control slot 54(FIGS. 6, 7) which cooperates with an alignment pin 56 (FIG. 2) that issecured in a hole in the recessed area 30 of the rear housing member 18.To positively locate the switch in “off,” “send,” and “return”positions, the fluid control switch 44 also includes three dimples 58(FIG. 6) that interact with a detent ball 60 and compression spring 62(FIG. 2), which are housed in a short lumen 64 (FIG. 3) within thecylindrical member 24.

As best seen in FIG. 7, the bottom of the fluid control switch 44includes a C-shaped connector channel 66 and an elliptical-shapedconnector channel 68. The control switch 44 is relieved about theC-shaped and elliptical-shaped connector channels 66, 68 in order toreceive o-rings 70 and 72, respectively, which seal the connectorchannels 66, 68 against the recess 30. To further prevent leakage aroundthe fluid control switch 44, an o-ring 74 is received in an o-ringchannel 76 about the exterior of the fluid control switch 44 (best seenin FIG. 6) and an o-ring 78 may be received by an o-ring channel aboutthe distal opening of the switch 44. The o-rings 70, 72, 76 and 78 arepreferably made of Buna-N or ethylene propylene.

In operation, when the fluid control switch 44 is in the “send”position, both the fluid injection channel 36 and the seed deliverychannel 42 communicate through the C-shaped connector channel 66.Simultaneously the hydraulic return channel 40 and the fluid exitchannel 38 communicate through the elliptical-shaped connector channel68. Thus, fluid is allowed to flow through the fluid injection channel36 through the C-shaped connector channel 66 and into the seed deliverychannel 42. Fluid that bypasses the treating elements reaches the distalend of the delivery catheter 14 and returns to the hydraulic returnchannel 40 and is allowed, through the elliptical-shaped connectorchannel 68, to flow through the exit channel 38.

When the fluid control switch 44 is in the “return” position, both thefluid injection channel 36 and the hydraulic return channel 40 arealigned through the C-shaped connector channel 66. Simultaneously, boththe seed delivery channel 42 and the fluid exit channel 38 are alignedthough the elliptical-shaped connector channel 68. Consequently, fluidis allowed to flow through the fluid injection channel 36 into theC-shaped connector channel 66 and through the hydraulic return channel40. As the treating elements are forced hydraulically from the distalend of the catheter back to the transfer device 12, fluid is allowed toflow from the seed delivery channel 42 to the fluid exit channel 38through the elliptical-shaped connector channel 68.

When the fluid control switch 44 is in the “off” position, the fluidinjection channel 36 is the only channel aligned with the C-shapedconnector channel 66. Thus, no outlet exists for fluid flowing to theconnector channel 66 from the fluid injection channel 36.

The transfer device 12 preferably includes a pressure relief valve (notshown) so that the system 10 cannot be over-pressurized. The valve wouldopen to allow fluid in the system 10 to escape once the fluid pressureexceeded a certain, pre-determined value. Once the pressure in thesystem returns to a safe level, the valve would close. In one form, thevalve may be spring-actuated, so that fluid pressure greater than thepre-determined value compresses the spring to open the valve, the valvebeing closed by the spring when the fluid pressure is reduced to belowthe pre-determined value. In addition, the transfer device 12 preferablyincludes an accumulator (not shown) or similar apparatus for maintaininga substantial amount of pressure against the radiation source train andmarker seeds while they are positioned at the distal end of the catheter14 so that they cannot migrate away from the distal end of the catheter14 and the treatment site during radiation treatment. The accumulatormay also be used to maintain a substantial amount of pressure againstthe treating elements and marker seeds so that they will remaincompletely within the lumen of the quartz sleeve 84 and visible to theusers when they are not being used for radiation treatment.

Distal of the rear housing 18 and connected thereto is the centralhousing and actuator switch/shuttle gate assembly 20. Proper alignmentof the rear housing 18 and the central housing and actuatorswitch/shuttle gate assembly 20 may be assured by alignment pins (notshown). The assembly 20 includes a central housing 80 having a centrallumen 82 for receipt of the quartz sleeve 84 (FIG. 8) which extends theentire length of the central housing 80 and in which the radiationsource train or seeds are stored.

The central housing 80 is cylindrical in shape and preferably made ofclear Lexan or clear polycarbonate. The quartz sleeve 84 is preferablymade of natural or synthetic quartz or quartz glass (fused quartz), orother materials consisting of natural or synthetic fused silica. A lumen86 extends the entire length of the quartz sleeve 84 and the radiationsource seeds and marker seeds are stored within the lumen 86 when theseeds are not being delivered to the treatment site. The quartz sleeve84 is used to shield the radiation emitted from the source train so thatthe transfer device 12 can be handled safely. The quartz material doesnot break down as a result of storing the radiation-emitting treatmentseeds and also remains clear so that the seeds can be visually detected.The quartz rod is of sufficient thickness to block at least 99 percentof the radiation. In practice, a thickness of 1 cm has been found to besufficient.

In order to more easily discern the presence of the radiation sourceseeds and marker seeds within the quartz sleeve 84, the sleeve is of oneuniform diameter and has no steps or o-rings disposed thereon. Thus, theentire length of the quartz sleeve can be seen. The lower half of thequartz sleeve 84 can be covered with a white film, preferably vinyl orTyvek®, to create a contrasting background for the source seeds.Additionally or alternatively, a magnifying piece may either encase thequartz sleeve 84 or lie along the top of the quartz sleeve to betterpermit visualization of the radiation source seeds. Additionally, alight source could be utilized to better visualize the source and markerseeds.

As best seen in FIGS. 3 and 9, a rear housing insert 88 with a lumentherethrough comprises an intermediate member between the rear housing18 and central housing 20 for providing fluid communication between theseed delivery channel 42 and the lumen 86 of the quartz sleeve 84through lumen 90 of the insert 88. The lumen. 90 is L-shaped andprecludes the treating elements from migrating into the rear housing 18,while insuring fluid communication between the rear housing lumens andthe quartz lumen.

A smaller, off-axis through-lumen 92 extends through the central housing80 (FIG. 10) and is a continuation of the hydraulic return channel 40 inthe rear housing 18. Fluid leakage between the connection of the returnlumen 40 and the rear housing 18 and the return lumen 92 in the centralhousing 80 is prevented by a means of an o-ring 94 (FIG. 2), preferablymade of Buna-N or ethylene propylene

An actuator switch 96 is located at the distal end of the centralhousing 80 that pivots a shuttle gate 98 to operate the system. Theactuator switch 96 allows for two positions: “connect/prime” and“send/retrieve.” The connect/prime mode allows for connection of theconnector 16 (FIG. 1) through the transfer device 12. After beingconnected, the connect/prime mode allows for flushing and priming of thetransfer device 12 and the catheter 14 without the delivery of theradiation source train.

The send/retrieve mode allows for the delivery of the radiation sourcetrain and marker seeds to, and retrieval from, the distal end of thecatheter 14. The send/retrieve mode of the actuator switch 96 cannot beaccessed unless the connector 16 has been locked into the transferdevice 12. This prevents inadvertent delivery of the radiation sourcetrain to any location other than the delivery catheter 14. To this end,the distal face of the central housing 80 includes a recessed area 100(FIG. 10) in the general shape of a squared U. The recess 100 receivesthe proximal end of positioning pin 102 (FIG. 2) to positively lock theactuator switch 96/shuttle gate 98 in position for two modes discussedabove.

The actuator switch 96 is made of a hard plastic material, such asAcetal or Delrin. The actuator switch 96 has a top portion 96 a (FIG.11) that has a depression so that the user may use solely a thumb or afinger to operate the switch. The actuator switch also includes twoslightly curved arms 96 b that extend outwardly and downwardly from themidsection of the switch 96. Two rectangular legs 96 c extend from thebottom of the switch 96, with each leg 96 c having a hole 96 dtherethrough for receipt of the positioning pin 102. Between the twolegs 96 c, a hollow portion extends into the midsection of the switch 96for receiving the top portion of the gate 98 and a compression spring104 (FIG. 2).

The shuttle gate 98 is made of a plastic material, such as Acetal orclear polycarbonate, and is of sufficient thickness to insure stabilitywhen the gate pivots. The shuttle gate 98 includes a body portion 106(FIG. 12) that has a shoulder and tapers inward to a curved bottom. Thebody portion 106 includes a hole 107 for receipt of a compression spring105 (FIG. 2) which biases the shuttle gate 98 toward the connect/primemode. A neck 108 extends upwardly from the body portion 106 of the gate98 and includes a hole 110 in which the compression spring 104 isreceived. Neck 108 also includes a slot 112 for receiving thepositioning pin 102. The gate 98 includes a through hole 114 at itsbottom for receipt of a pivot pin 116 (FIG. 2), so that the gate 98 canrotate about the pivot pin 116. The gate 98 also includes a hole 118between the axis pin hole 114 and the positioning slot 112 that is largeenough to allow the treating elements to pass therethrough. An o-ringgroove 120 exists on each side of the gate for receiving an o-ring 122(that encircles the proximal opening of the seed hole) and an o-ring 124(that encircles the distal opening of the seed hole). The o-rings 122,124 (FIG. 2) are located so that when the actuator switch/shuttle gateare moved between their various locations, the o-rings do not travelacross the edges of any other parts, thus reducing wear on the o-ringsand providing for smoother action when operating the gate 98.

In operation, the compression spring 104 biases the actuator switch 96away from the shuttle gate 98. When the actuator switch 96 is presseddownward against the force of the compression spring 104, thepositioning pin 102 is moved towards the bottom leg of the U-shapedrecess 100 in the central housing 80 and the collar housing 146 topermit movement of the actuator switch 96 and the shuttle gate 98between the two positions.

The shuttle gate 98 is secured to the distal end of the central housing80 by a gate housing 126. As best seen in FIG. 13, the proximal side ofgate housing 126 has a recessed area 128 in the general shape of shuttlegate 98 and a generally rectangular opening 129. When the gate 98 is inthis recessed area 128 the neck 108 extends beyond the gate housing 126.The gate housing 126 includes a seed lumen 130 which is chamfered atboth its proximal and distal ends to facilitate the delivery of thetreating elements. (The seed lumens in the other housings may also bechamfered at their ends to facilitate delivery of the treatingelements.)

The distal side of the gate housing 126 (best seen in FIG. 14) has acircular recessed area 132 with a beveled edge encircling the seed lumenfor better alignment with the connector 16. For alignment of the gatehousing 126 with the central housing 80 and a collar housing 146, thegate housing 126 also has holes 136 for receiving screws 138 (FIG. 2)and an alignment hole 140 for receiving alignment pins 142, 144 (FIG.2). The gate housing 126 also includes a fluid return channel 148 (acontinuation of the fluid return channel 92 in the central housing 80)and an annular groove 150 on the proximal side of the gate housing 126for receipt of an o-ring 152 (FIG. 2). An aperture 154 on the proximalside of the gate housing receives the distal end of the pivot pin 116for the shuttle gate 98.

The collar housing 146 is positioned intermediate the gate housing 126and a front housing 156. The proximal face of the collar housing 146(FIG. 15) is shaped similarly to the distal face of the central housing80 (FIG. 10) and includes a recess 158 that compliments the recess 100in the central housing 80 and receives the distal end of the positioningpin 102 of the shuttle gate 98.

The collar housing 146 has an enlarged central opening 160 for receivingthe connector 16 (FIG. 1) and which is relieved on the proximal side ofthe collar housing 146 for receipt of o-ring 134 (FIG. 2). A rectangularopening 161 extends through the collar housing 146. The collar housing146 includes a fluid return channel 162 (a continuation of the fluidreturn channel 148 in the gate housing 126) with an annular o-ringgroove surrounding the proximal opening thereof for receipt of o-ring164 (FIG. 2). An alignment hole is also included for receipt ofalignment pin 144 to align the collar housing 146 with the gate housing126 and another hole for receiving alignment pin 166 for aligning thecollar hosing 146 with the front housing 156.

Cut-outs on the distal face of the collar housing 146, withcomplimentary cut-outs in the proximal face of the front housing 156,receive a release button 168, release switch 170, and release trigger172, which cooperate to receive and lock the connector 16 into thetransfer device 12 and to release the connector 16 from the transferdevice 12 as well. The interaction of the release button 168, releaseswitch 170, and release trigger 172 are described in greater detailbelow.

The release trigger 172 (FIG. 16) includes a generally rectangular body172 a with two legs 172 b extending therefrom. A sloped relief ofparabolic shape 172 c on the distal side of the trigger 172 makes up theedge between the two legs 172 b. The top of the release trigger 172includes a shallow bore 172 d for receiving one end of a compressionspring 174 (FIG. 2).

The release switch 170 (FIG. 17) includes an elongated rectangular body170 a with a curved and notched ramp 170 b at one end and a protrudingarm 170 c (FIG. 18) at the other end. The arm 170 c includes a bore 170d for receipt of a dowel pin 176 (FIG. 2). The release button 168 issecured to the release switch 170 by means of a screw 178 (FIG. 2) thatis received in a hole 170 e in the release switch 170. Alternatively,the release button 168 may be an integral part of the release switch170.

The front housing 156 completes the distal end of the transfer device 12and includes a central lumen 180 (FIG. 19) for receiving the connector16. The distal portion of the central lumen 180 is relieved at 181 (FIG.20) to seat two o-rings that fit on the outside of the connector 16 whenthe connector is locked into the transfer device 12 (to seal theconnection between the connector 16 and a fluid return lumen 184 in thefront housing 156. The front housing 156 includes two holes 182 forreceiving the screws 138 that secure the front housing 156, collarhousing 146, and gate housing 126 to the central housing 80. Asdescribed above, the lumens in the central housing 80 that receive thescrews 138 can optionally be lined with helical, coiled wire inserts orinclude threaded metal inserts to provide a more durable connection. Thefront housing 156 also includes a fluid return lumen 184 (a continuationof the fluid return lumen 162 in the collar housing 146) that has anannular o-ring groove surrounding the proximal opening for receipt of ano-ring 186 (FIG. 2). An aperture in the proximal face receives alignmentpin 166 for insuring alignment of the front housing 156 with the collarhousing 146.

Turning now to the operation of the actuator switch/shuttle gate, whenthe gate 98 is in the closed position (and the connector 16 is notconnected to the transfer device 12), the release switch 170 rests upona compressed spring 190 (FIG. 2) with one of the legs 172 b of therelease trigger 172 engaging the uppermost portion of the ramp 170 b ofthe release switch 170 to keep the release switch pressed down againstthe compressed spring 190 (FIG. 19a). In this condition, the releasebutton 168 is completely recessed in the opening between the collarhousing 146 and front housing 156. The end of the dowel pin 176 extendsthrough the openings 129 and 161 in the gate housing 126 and collarhousing 146, respectively, at the bottom of the openings 129, 161 and ispositioned adjacent to gate 98 to prevent the gate from pivoting to andengaging in the seed transit mode.

When the connector 16 is inserted into the central lumen 180 of thefront housing 156, the proximal end of the connector 16 contacts thesloped relief 172 c of the release trigger 172 to force the trigger 172upwardly, while simultaneously compressing the spring 174 (FIG. 19b). Asthe release trigger 172 moves away from the release switch 170, movementof the release switch 170 is no longer impeded and the release switch,biased by the compressed spring 190, moves upwardly until the curvedramp 170 b engages an undercut section on the connector 16. This locksthe connector 16 into the transfer device 12. When the release switch170 is moved to lock onto the connector 16, the release button moves outof its recessed area to visually confirm that the connector 16 is lockedinto the transfer device (FIG. 19c). Simultaneously, the dowel pin 176moves to the top of the openings 129, 161 so that it no longer preventsthe gate 198 from engaging into the seed transit mode.

The actuator switch 96 can now be moved from the connect/prime mode tothe seed transit mode by pushing down on the actuator switch 96 to forcethe positioning pin 102 downward to the bottom of the grooves 100 (inthe central housing 80) and 158 (in the collar housing 146). Whilemaintaining a downward force on the actuator switch 96, a horizontalforce is then applied to the actuator switch 96 to move the positioningpin 102 through the horizontal groove of the recesses 100, 158 to theother vertical groove. The switch 96 is then released and thepositioning pin 102 moves up to the top of the vertical groove to placethe switch 98 in the seed transit mode. When the actuator switch 96 isengaged in the seed transit mode, the gate 98 is positioned so that aportion of the gate 98 now occupies the same space that was occupied bythe dowel pin 176 in the connect/prime mode.

To remove the connector 16 from the transfer device the actuator switch98 is moved into the connect/prime mode after all the treating elementsand marker seeds have been returned to the quartz sleeve 84. Once theactuator switch 98 is in the connect/prime mode, the release button 168is pressed inwardly to move the release switch 170 downwardly againstthe spring 190. The dowel pin 176 simultaneously moves so as to preventmovement of the gate 98 back to the seed transit mode. The connector 16can then be manually withdrawn from the transfer device. Withdrawal ofthe connector 16 allows the release trigger 172 to be forced by thespring 174 to drop down and reposition one of its legs 172 b in front ofthe ramp 170 b, returning the release button 168, the release switch170, and the release trigger 172 to their initial positions.

The release button 168 cannot be activated while the actuator switch 96is in the seed transit mode. In the seed transit mode, the gate 98 ispositioned so that it hinders downward movement of the dowel pin 176.Because the dowel pin 176 is connected to the release switch 170,downward movement of the release switch 170 is also impeded and thecurved ramp 170 b cannot disengage from the connector 16.

Turning to FIGS. 21-7, there is seen a further embodiment of the rearhousing/fluid control switch for use in the transfer device 12 of thepresent invention. As seen in FIG. 21b, the rear housing 200 isgenerally cylindrical in shape and includes two axial through-lumens 202for positioning two screws (such as screws 28 in FIG. 2) to secure therear housing 200 to the central housing. The rear housing includes tworecesses 204, 206 for receipt of luer fittings or connectors similar toconnectors 32, 34 shown in FIG. 2. Such luer fittings would be securedin the recesses 204, 206 by means of an adhesive. The luer fittings maybe partially or completely recessed within the rear housing 200.Preferably the luer connector received in recess 204 provides forattachment to a liquid or gas filled device (not shown) that is used forhydraulic or pneumatic delivery and retrieval of the radiation sourcetrain and marker seeds to and from the delivery catheter 14. The luerconnector secured in recess 206 attaches to a fluid collection bag (notshown).

Toward the distal end of the rear housing 200 there is a cylindricalbore 208 that receives the fluid control switch 210, which will bedescribed in detail later. The diameter of the cylindrical bore 208 isslightly smaller than the largest diameter of the fluid control switch210 so that the fluid control switch 210 fits tightly within the bore208. A fluid inlet channel 212 connects recess 204 to the cylindricalbore 208 (FIG. 22); a fluid exit channel 214 connects recess 206 to thecylindrical bore 208 (FIG. 23); a fluid return/seed retrieval channel216 connects the cylindrical bore 208 with an opening 218 in the distalface of the rear housing 200 (FIG. 22 or 23); and a fluid return/seeddelivery channel 220 connects the cylindrical bore 208 to a centraldistal opening 222 including a rear housing insert 224 (similar toinsert 88 in FIG. 9) (FIG. 22 or 23).

The fluid control switch 210 is a solid cylinder, preferably made of awhite or clear Teflon material to allow smooth movement of the cylinder210 within the central bore 208, and includes four fluid channels(described below) for selectively connecting channels 212 and 214 withchannels 216 and 220. The switch 210 includes a rectangular cut-out 226at its upper end for receipt of handle 228 the rectangular cut-out 226is sized so that the distal end 230 of the handle 228 fits snugly withinit.

The handle 228 is enlarged at its distal end 230 so that it has anoverhang or step 231. When the distal end 230 of the handle 228 isfitted into the rectangular cut-out 226 in the fluid control switch 210,and the fluid control switch 210 is positioned in the cylindrical bore208 of the rear housing 200, the entire overhang 231 is positionedwithin the circumference of switch 210, and the overhang 231 of thehandle 228 abuts the sidewall of the central bore 208, thus preventingremoval of the handle 228 from the cut-out 226 and securing the handle228 within the switch 210.

The fluid control switch 210 includes four channels 242, 244, 246, and248 for selectively connecting the fluid inlet channel 212 and fluidexit channel 214 with the fluid return/seed retrieval channel 216 andfluid return/seed delivery channel 220. As best seen in FIGS. 26 and 27,the fluid control switch 210 includes a seed delivery channel 242, afluid return channel 244, a seed retrieval channel 246, and a fluidreturn channel 248.

In operation, when the fluid control switch 210 is in the “send”position, both the fluid inlet channel 212 and the seed delivery channel220 in the rear housing 200 communicate through the seed deliverychannel 242 in the fluid control switch 210. Simultaneously, the fluidexit channel 214 and fluid return/seed retrieval channel 216 in the rearhousing 200 communicate through fluid return channel 248 in the fluidcontrol switch 210. Thus, fluid is allowed to flow from, e.g., asyringe, through the fluid inlet channel 212, through the seed deliverychannel 242 in the switch 210, and into the seed delivery channel 220 toadvance the treatment elements to the distal end of the deliverycatheter. Fluid that bypasses the treatment elements reaches the end ofthe delivery catheter and returns to the fluid return/seed retrievalchannel 216 and is allowed, through the fluid return channel 248 in theswitch 210, to flow through the fluid exit channel 214 and into, e.g., afluid collection bag.

When the fluid control switch 210 is in the “retrieval” position, boththe fluid inlet channel 212 and the fluid return/seed retrieval channel216 in the rear housing 200 communicate through seed retrieval channel246 in the fluid control switch 210. Simultaneously, both the fluid exitchannel 214 and the seed delivery channel 220 in the rear housing 200communicate through the fluid return channel 244 in the fluid controlswitch 210. Consequently, fluid is allowed to flow through the fluidinlet channel 212, into the seed retrieval channel 246, through thefluid return/seed retrieval channel 216, and into the catheter tohydraulically force the treating elements from the distal end of thecatheter back to the transfer device. Simultaneously, fluid is allowedto flow from the seed delivery channel 220, through the fluid returnchannel 244, into the fluid exit channel 214, and out of the transferdevice.

When the fluid control switch 210 is in the “off” position, none of thechannels 212, 214, 218, 220, 242, 244, 246, and 248 communicate witheach other. Thus, no outlet exists for any fluid from the fluid inletchannel 212.

The fluid control switch 210 includes a channel or groove 250 thatreceives o-ring 252 to prevent leakage out of the cylindrical bore 208(FIGS. 24, 25). The fluid control switch 210 also includes three areasof enlarged diameter, generally indicated by 254, to prevent cross-talkamong the fluid channels 242, 244, 246 and 248. These areas of enlargeddiameter correspond with the openings of the channels 242, 244, 246, 248and create a tight seal about the fluid openings. Alternatively, o-ringscould be used in place of the areas of greater diameter.

On the distal face of the fluid control switch 210 there is an oblongopening 232 (FIG. 27) which extends radially along the face of theswitch 210 so that, when the switch 210 is placed within the cylindricalbore 208, the oblong opening 232 aligns with a short through lumen 234in the rear housing. The oblong opening 232 terminates internally of thefluid control switch 210 with three dimples 236 which interact with acompression spring 238 and detent pin 240 (FIG. 21b) to assist in thepositioning of the fluid control switch 210 (similar to the compressionspring 62 and ball detent 60 shown in FIG. 2). The ends of the oblongopening 232 act as stops in conjunction with the detent pin 240 to limitthe degree to which the fluid control switch 210 can be rotated.

The detent pin 240 has a ball-shaped end that rests within the dimples236. In the “off” position the detent pin 240 rests within the middledimple. As the fluid control switch 210 is moved to either the “send” orthe “retrieval” mode, the middle dimple moves away from the detent pin240, while either end dimple moves towards the pin. As the switch 210and dimples rotate, the detent pin is pushed back against thecompression spring 238. As one of the end dimples becomes aligned withthe pin, the force of the spring 238 propels the pin 240 forward so thatthe ball of the pin 240 rests within the dimple. Because when the pinmoves away from the dimples during rotation of the cylinder it does notmove outside of the opening 232, the pin secures the cylinder 210 withinthe rear housing 200 at all times.

Turning to FIGS. 29-33, there is seen an improved transfer device 300for handling and delivering the treating elements in conjunction withthe intraluminal radiation system of the present invention. In contrastto the previously described transfer devices 12, the transfer device 300includes an ergonomically designed exterior that is more easily grippedby the user. Additionally, the various internal components of thetransfer device 300 are unitized for easier construction and assembly.The transfer device 300 also features additional or improved safetyfeatures, such as treatment seed detection circuit and display, a fluidpressure indicator/relief valve, and a catheter connector/seed or pingate interlock, all of which are described in greater detail below.

Turning to the exploded view of FIG. 31, it can be seen that thetransfer device comprises a two-part shell, including shell halves 302 aand 302 b which enclose a chassis 304, on which the various componentsof the transfer device 300 are mounted. The shell half 302 a includes amagnifying window 306 for viewing the quartz sleeve or housing 308having a lumen 308 a that holds the treatment seeds (not shown),indicator lights or “annunciators” comprising LEDs 310 a and 310 b (FIG.30) that indicate whether the treatment seeds are residing in the quartzsleeve or elsewhere in the transfer device and its associated catheter,a power button 312 for activating the LED seed detection/indicatorsystem, a pressure indicator window 314 for providing a visualindication of the fluid pressure within the treatment system, and afluid control button 316 (similar in function to fluid control handle 44or 228 described above) for actuating the fluid control switch. Alongthe side of the housing shell half 302 a are a release button 318 forthe catheter connector (similar in function to the release button 168described above), and a sliding gate actuator switch 320 that covers therelease button 318 to prevent the unintentional release of the catheterconnector when the treatment seeds are being transferred to or areinside of the catheter. The transfer device 300 also includes acompartment 319 at its proximal end (FIG. 33) for receiving a fluidcollection bag (not shown).

Turning to FIGS. 29A and B, the transfer device 300 is shown with adetachable syringe 322 which provides the pressurized fluid forhydraulic delivery and retrieval of the treatment seeds used in thesystem. The syringe 322 is connected to the transfer device by a luerlock 324 and is supported on the transfer device by a saddle having twooff-set arms 326 a and 326 b (best seen in FIGS. 30 and 31) that extendfrom shell halves 302 a and 302 b, respectively, and wrap around thebarrel 322 a of the syringe 322 to firmly hold the syringe to thetransfer device. As can be seen in FIGS. 29A and B, the syringe 322 isheld at an angle from the longitudinal axis of the transfer device topermit easier manipulation of the syringe plunger 322 b.

As indicated above, the interior components of the transfer device 300are constructed separately and are mounted to the chassis 304, wherethey are preferably joined together for fluid communication by means ofpolyethylene tubing (not shown) and barbed connectors such as, e.g., 328(FIG. 31). This type of construction may permit simpler and moreeconomical construction and assembly of the transfer device than thepreviously described embodiments in which, e.g., the various housingmembers (and their respective fluid passageways) and the fluid controlswitch are machined from blocks of solid material that have to be joinedtogether. For example, the fluid control switch 330 of the transferdevice 300 may comprise a standard four port valve body, such as valvemodel no. 7017KV, manufactured by the Kloehn Co. of Brea, Calif., ratherthan the custom-machined switches 44 (FIGS. 1, 2, 6, 7) or 210 (FIGS.21B, 24-27) and their respective interfitting rear housing members 18,200.

With reference to FIGS. 29B, 31, and 37, the chassis 304 of the transferdevice 300 also supports a pressure indicator/pressure relief valve,generally indicated by 332, that is visible through the pressureindicator window 314 on shell half 302 a. The pressure indicator/reliefvalve 332 is in fluid communication with the syringe 332 and is designedto provide an easily-readable visual indication of the relative fluidpressure in the treatment system and to release the fluid to thereservoir when it exceeds a predetermined maximum valve (e.g., 100 psi),thus insuring that the fluid pressure does not attain a level that couldpossibly damage either the transfer device or its associated catheter.

With reference to FIGS. 35A-D, the pressure indicator/relief valvecomprises a cylinder 334 with having an inlet port 336 in fluidcommunication with the syringe 322. The cylinder 334 has a graduatedinside diameter, the smaller-diameter portion 338 a, being, e.g., 0.375in., and the larger diameter portion 338 b being, e.g., 0.399 in. (FIGS.35A and B). The cylinder 334 houses a piston 340 sized to fit in thesmaller diameter portion 338 a of the cylinder 334, and a spring 342 isinterposed between the piston 340 and the end wall of the largerdiameter portion 338 b of the cylinder. The spring 342 has a springconstant and length selected to maintain the piston 340 insmaller-diameter portion 338 a of the cylinder 334 until the fluidpressure reaches the predetermined maximum. When the spring 342 issufficiently compressed by the fluid pressure to permit the piston 340to move into the larger-diameter portion 338 b of the cylinder 334(i.e., when the pressure reaches 100 psi), fluid passes around thepiston into the larger-diameter portion 338 b of the cylinder and exitsthrough an outlet 344 that is in fluid communication withlarger-diameter portion 338 b of the cylinder. Once the fluid pressurein the system is below the predetermined maximum, the spring 342 biasesthe piston 340 back into the smaller diameter portion 338 a of thecylinder.

As presently contemplated, the piston 340 comprises two parts 340 a and340 b that interfit to create a relieved interface which seats a seal(not shown) that maintains fluid-tight contact between the piston 340and the smaller-diameter portion 338 a of the cylinder 334. The pistonmay be manufactured of a white Delrin material and the seal may be aring seal, such as that manufactured by Bal Seal Engineering Company ofSanta Ana, Calif. under part no. 410 MB-010-G-316. The cylinder 334 maybe made of a clear polycarbonate, having a polished inside diameter andgraduation markings (not shown) on the outside thereof which are visiblethrough the pressure indicator window 314. The graduation markingspermit the user to have a visual indication of the fluid pressure in thesystem based upon the relative position of the piston 340 within thecylinder 334. Further, the spring 342 is preferably stainless steel,such as that manufactured by the Lee Spring Company of Brooklyn, N.Y.having a stock no. of LCM-110E-13-S, standard series. Of course, variousother pressure gauges and relief valves as are well-known in the art maybe utilized in place of the spring-loaded piston and cylinderarrangement described above.

Like the above-described embodiments, the transfer device 300 alsoincludes a release trigger/release switch mechanism 350 (FIG. 31) forreceiving and locking the catheter connector into the transfer device(similar in appearance and operation to the release trigger 172/releaseswitch 170 described above and shown in FIGS. 16-19). The transferdevice 300 further includes a pin gate 352 distal of the quartz seedsleeve 308 that blocks the seed lumen to prevent treatment seeds fromexiting the transfer device, while still permitting fluid to flowthrough the seed lumen for, e.g., priming the system. However, thetransfer device 300 includes a safety interlock between the releasetrigger/release switch 350 and the pin gate 352, generally indicated by354 (best seen in FIG. 40A) that prevents the release switch from beingdepressed (and thus preventing the user from removing the catheterconnector from the transfer device) if the pin gate is retracted to aposition that permits treatment seeds to pass through the seed lumen.

Turning to FIGS. 29B, 31, 32B and 32C, there is seen a separate blockmember 356 that supports on the chassis 304 the release trigger/releaseswitch mechanism 350 and pin gate mechanism 352, generally describedabove, as well as the quartz sleeve 308 and seed verification system(which is described in greater detail below). Similar to the releaseswitch 170 described above, the release switch 358 (FIG. 38) includes abody portion 358 a, preferably made of a Delrin material, with a curvedand notched ramp 358 b at one end, and the release button 318 secured bya screw 360 (FIG. 31) at the opposite end. Alternatively, the releasebutton 318 may be an integral part of the release switch 358. Asdescribed above in connection with release switch 170 and releasetrigger 172, the curved and notched ramp 358 b of release switch 358engages a circumferentially relieved section 362 on the catheterconnector 364 (FIG. 41) to lock the connector into the transfer device.The release switch 358 is depressed to disengage the curved and notchedramp 358 b from the catheter connector 364 to permit removal of theconnector from the transfer device.

As illustrated, the pin gate 352 (FIGS. 39A, B) is preferably made ofstainless steel and has a T-configuration comprising a separate enlargedbody 352 a that terminates in a slender cylindrical elongated member 352b. A transverse head 352 c is supported by the body portion 352 b of thepin gate 352. The elongated member 352 b of the pin gate 352 has adiameter that is less than the diameter of the seed lumen, so that wheninterposed through the seed lumen it will block passage of treatmentseeds, but allow fluid to pass.

The pin gate 352 is actuated by means of a slider block 366 which isreceived in an elongated slot 368 (FIG. 31) in the block member 356 andis manipulated by the gate actuator switch 320. With reference to FIG.40B, the slider block 366 includes two generally L-shaped legs 370 a and370 b connected to the proximal end of the slider block, with the freeends of the legs forming a ramp that engages the transverse head 352 cof the pin gate 352 (best seen in FIG. 32c) to move the pin gate out ofthe seed lumen when the slider block 366 is moved in a proximal todistal direction. The legs 370 a, 370 b straddle a guide track 372 (FIG.32A) formed in the block member 356. A pivoting lock 374 (FIGS. 32C, 40Aand 40C) is biased by a spring steel (24 GA) leaf spring 376 to urge thetransverse head 352 c of the gate pin 352 down the ramp formed by thelegs 370 a and b when the slider block 366 is moved in a distal toproximal direction, thus causing the pin gate 362 to block the seedlumen. The leaf spring 376 is preferably supported on a block 378 thatis secured to the block member 356 by two screws 380 received in tappedholes in the block member 356. It is contemplated that each of theslider block 366, pivoting lock 374 and block 378 will be made ofaluminum.

In keeping with the invention, an interlock mechanism is providedbetween the release switch 358 and the slider block 366. Specifically,the distal end of the slider block 366 includes a extending shaft 382that prevents the slider block 366 from moving in a proximal to distaldirection to retract the pin gate 352 unless the shaft 382 is alignedwith a through-hole 358 c in the body portion 358 a of the releaseswitch 358. (A similar shaft 384 extends from the proximal side of theslider block 366 to limit motion of the slider block in a distal toproximal direction.) However, the through-hole 358 c only aligns withthe shaft 382 when the catheter is connected to the transfer device andthe curved and notched ramp 358 b on the release switch 358 engages therelieved section 362 of the catheter connector 364. Thus, the pin gate352 cannot be retracted by the slider block 366 unless the catheter isconnected to the transfer device to align the through-hole 358 c withthe shaft 382. In addition, when the shaft 382 extends through the hole358 c, the release switch 358 cannot be depressed, thus preventing therelease switch 358 from disengaging the relieved section 362 on thecatheter connector. Accordingly, the catheter cannot be released by thetransfer device if the pin gate is retracted. As an added safetyfeature, the gate actuator switch 320 is configured to at leastpartially cover the release button 318 on the release switch 358 whenthe pin gate 352 is retracted (best seen in FIG. 32C), thus preventingthe release button 318 from being depressed.

In keeping with a further aspect of the invention, the catheterconnector 364 is provided with a detent that interlocks with thetransfer device 300 that must be manually actuated simultaneously withdepressing the release button 318 to release the catheter connector 364from the transfer device. This provides for added safety in that removalof the catheter from the transfer device requires a coordinated actionof both hands of the operator.

Turning to FIGS. 41A-C there can be seen the catheter connector 364which includes a central plug portion 386 having a through lumen 388,which receives a connector insert 390 (FIGS. 41E and D, described below)and a sleeve member 392 that overlies the distal portion of theconnector 394 a, i.e., that portion which remains external to thetransfer device when the connector is connected thereto. The proximalportion of the connector 394 b is received in the transfer device.

The central plug portion 386 of the connector 364 includes two integral,radially-opposed cantilever arms 396 that are connected to the distalend of the central plug 386 and extend axially along, but spaced awayfrom, the central plug portion. The proximal ends of the arms 396include transverse detent tabs 398 that, when the connector is insertedinto the transfer device, snap into contact with a projecting shoulder400 (FIG. 32C) in the distal end of the transfer device, thus securingthe connector in place. To disengage the connector from the transferdevice, the cantilever arms 396 must be depressed radially inwardly toallow the detente tabs 398 to clear the shoulder 400. Simultaneously,the release button 318 must be depressed to disengage the release switch358 from the connector.

In order to prevent foreign matter from contacting the exit of thetransfer device through the slots between the cantilever arms 396 andthe central plug 386, the sleeve member 392 is fitted over the distalend 394 a of the connector, with the proximal end of the sleeve 392abutting the distal end of the transfer device when the connector isattached thereto. The sleeve member 392 is sufficiently flexible topermit manipulation of the cantilever arms 396 to permit removal of thecatheter.

The connector insert 390 (FIGS. 41E and D) has an inner through lumen402 which is twice stepped along the distal portion of the insert 390.The insert 390 is molded to the most proximal end of the catheter body404 (seed and fluid return lumens only) and shield tubing 406. Theproximal ends of shield tubing 406 and catheter body 404 reside withinthe stepped portions of the insert 390, and a third channel 408 fluidlyconnects the seed lumen of the catheter with the chamfered proximal end410. A second bifurcation 412 occurs within the insert so that the fluidreturn lumen angles away from the seed lumen and communicates to theexterior of the catheter connector 364 through a curved channel 414exiting the insert 390 and in alignment with an opening 416 in the sidewall of the catheter connector 364. The catheter connector 364 slidesover the catheter insert subassembly 418 (FIG. 42A) for positioning theinsert 390 within the catheter connector 364. The proximal end of theinsert 390 is aligned with the proximal end of the catheter connector364 and UV cure adhesive is injected into other openings 420 through theconnector side wall. The adhesive flows into void areas within thecatheter connector through lumen and permanently secures the insert 390within the catheter connector 364. Alternatively, the catheter connector364 can be molded over the insert 390 after the insert has been moldedto the two lumen catheter portion.

The chamfered portion 410 of the catheter connector 364 fits over amated projection 422 (best seen in FIG. 32C) at the distal end of theblock member 356. This fit properly seats the catheter connector 364 formaximum alignment between the connector lumen and the fluid lumen in theblock member 356 and minimizes leakage of fluid at the catheterconnector/block member interface.

Turning to FIGS. 42A-D, the catheter 424 of the present invention issimilar to the catheters discussed in the above-identified co-pendingapplications. The catheter 424 has a proximal end 426, a distal end 428,and an elongated portion 430 therebetween. As best seen in FIG. 42D, thecatheter 424 has a seed lumen 432, a fluid return lumen 434, and a guidewire lumen 436. The seed lumen 432 and the fluid lumen 434 arecontiguous from the proximal end 394 b of the catheter connector 364 tothe distal end 428 of the catheter 424 and communicate with one anotherat the distal end 428 of the catheter 424 through an intraluminalconnector 438 (FIG. 42C) which is located in the seed lumen 432. Theintraluminal connector 438 is preferably made of stainless steel andalso reinforces the distal end 428 of the catheter 424 to prevent thetreating elements from exiting the distal end of the catheter.

The catheter 424, its seed lumen 432, and its guide wire lumen 436 areall of a generally round cross-section as seen in FIG. 42D. The fluidreturn lumen 434, however, has an elliptical cross-section to increasethe area for fluid flow without compromising the outer diameter of thecatheter 424. The greater area lowers the pressure required to sendmaintain, and return the treating elements. It also decreases the timeit takes to transfer the treating elements from the transfer device 300to the distal end 428 of the catheter 424 and vice versa. However, thefluid return lumen 434 may be of any size or shape to provide foroptimal transfer of the treating elements using a limited volume offluid.

For uniform dosing, it may be determined that the treating elements needto be positioned at or near the center of the luminal wall. In thatcase, the seed lumen 432 may need to be positioned as close as possibleto the center of the catheter 424 to prevent the seed lumen 432 andradioactive elements from lying too close to one side of the luminalwall.

The catheter 424 is preferably made in a single extrusion of 100% lowdensity polyethylene which is very flexible, soft and lubricous. Thesecharacteristics allow the catheter 424 to be inserted over a guide wireand into an endoluminal area within the human body without damaging theluminal walls. If a catheter 424 made of 100% low density polyethyleneis too soft or pliable, then a polyethylene blend which consists of acertain percentage of both high and low density polyethylene may beused. To maintain flexibility of the catheter, the polyethylene blendmust have a higher percentage of low density polyethylene.

Returning to FIGS. 42A-C, an atraumatic tip 440 having a small taper(preferably 11 degrees or less) and a small distal tip radius is fused(possibly with radiofrequency energy) to the distal end 428 of thecatheter 424. The fusing process melts the seed lumen 432 and the fluidreturn lumen 434 closed. The tip 440 is made of polyethylene andpreferably with ethylene vinyl acetate. The guide wire lumen 436 extendsthrough the tip 440 and is lined with a sleeve 442 (FIG. 42C) of highdensity/low density polyethylene. This sleeve 442 is made of a materialthat is of a higher durometer than the tip 440 to resist the guidewirefrom tearing the tip 440 as the catheter 424 is delivered over aguidewire.

Radiopaque marker bands 444 made from platinum (90%)-iridium (10%) arelocated at the distal end 428 of the catheter 424 to assist in properplacement of both the catheter 424 and the treating elements. The markerbands 444 are secured to and flush with the exterior of the catheter424. Alternatively, radiopaque markers may consist of radiopaque ink ortiny radiopaque particles printed or blasted onto the exterior of thecatheter 424. The proximal portion 426 of the catheter may also have adepth marker (not shown) to indicate when the catheter is near the endof the guide wire so that the fluoroscopy can be turned on just prior tothe delivery of radiation.

The proximal end 426 of the catheter also has a bifurcation 446 wherethe guide wire lumen 436 branches off from the catheter portion 430 to aguide wire extension tubing 448. The guide wire extension 448 mayinclude a standard luer 450 with or without a valve for preventing thepatient's blood from exiting the proximal end of the guidewire lumen436. The guide wire extension tubing 448 and the bifurcation 446 can bemade of polyethylene or a blend of polyethylene and ethylene vinylacetate. The seed lumen 432 and the fluid return lumen 434 remaincontiguous throughout the bifurcation 446. Strain relief tubing 452 isplaced over the proximal end of the catheter portion 430 and extends ashort distance from the distal end of the bifurcation 446 where it issecured. The strain relief tubing 452 adds rigidity near the bifurcation446 for protection from kinks or other damage to the catheter 424. Also,the shield tube 406 fits over the catheter end proximal to thebifurcation 446 for additional protection from the radioactive treatingelements as they are transferred into and out of the catheter 424.

At specific times during the radiation therapy procedure, it may benecessary or desired to determine the position of the treating elementsand marker seeds with respect to the quartz housing 308 in the transferdevice 300. For example, assuming the radiation source train comprisestwelve stainless steel encapsulated radioactive treating elements withan inert gold marker seed at each end, the user may need to verify thatall twelve treating elements and two marker seeds are present within thequartz housing 308 before delivery of the elements to the distal end ofthe catheter 424, and for safety reasons must be sure that all of thetreating elements and marker seeds are within the quartz housing 308prior to closing the pin gate 352 and disconnecting the catheter 42&from the transfer device 300.

To determine whether or not all of the treatment elements are within thequartz housing 308, an electronic detection system (shown schematicallyin FIG. 45), which measures the presence or non-presence of the distalgold marker seed at a single position within the lumen 308 a in thequartz housing 308, is included in the transfer device 300. The systemdetects a gold marker calorimetrically by shining light of differentwavelengths onto the small area where the gold marker should residewithin the quartz housing 308 and measuring the reflectivity. Based onthe wavelength/reflection ratios of different light, the systemdetermines whether a gold object (gold marker) or non-gold object(stainless steel seed, background, or saline filled lumen 308 a in thequartz housing 308) is occupying the area. If a gold marker seed isdetected within the small area, it would be reasonable for the user tobelieve that it is the distal marker seed and that all of the elementsproximal to the distal marker seed are also within the quartz housing308. To increase the degree of certainty that all seeds are within thequartz housing 308, the electronic sensor can be enhanced to determinewhether or not both marker seeds are properly positioned within thequartz housing, and/or determine actively whether some or all stainlesssteel treating elements are properly positioned with the quartz housing.However, this would require providing more space within the housing ofthe transfer device 300 for the additional electronic and opticalcomponents.

In addition to detecting the absence or presence of gold marker at aspecific position along the quartz lumen 308 a, the electronics wait ina low power state for the power button 312 to be pressed. Then the twoindicator LEDs 310 a and 310 b are flashed on and off for severalseconds after the power button 312 has been pressed to indicate that theLEDs 310 a and 310 b and battery 454 are functional, and then indicatewhether or not a gold marker is detected by illuminating one of twoindicator LEDs 310 a, 310 b. A single C-cell lithium battery 454 isshown in FIGS. 29B, 31, 32B and 37 for powering the electronic system.However, the electronic system is preferably powered by two thinbatteries which are used in series to produce +6v from a single batterypack. The output is also inverted to produce a −6v voltage. Finally, theelectronics automatically return to the low power state after one minutehas elapsed to conserve the battery power, or restart the one minutetiming period if the button is pressed again during that one minute.

Referring to the logic diagram shown in FIG. 45, the battery isindicated by 456. The power supply is controlled by a sleep circuit.Applying power turns the sleep circuit of f which in turn shuts down thepower supply so that it draws only enough power to keep the systemalive. The on-switch 458 is a normally open push button switch 312. Whenthe switch 458 is closed by pressing the button 312 from the exterior ofthe transfer device 300, the sleep circuit wakes up and turns on thepower supplies 460, 462, one generating +6v and the other generating−6v. The power generated is first applied by starting an internal timer464 set for approximately one minute. This internal timer 464 is ananalog circuit, but can be a digital circuit using a counter for greaterprecision and longer times. At the end of one minute the power supplies460, 462 are turned off and the sleep circuit goes back to sleep untilthe next time the switch 458 is closed. If the button 312 is pressedduring the one minute timing period, the timing period is reset allowingthe power to stay on longer than one minute in total. The internal timer464 can be designed for other lengths of time. Each time the one minutetimer 464 is started, a four second test phase 466 also begins andenables a four Hz oscillator 468 which generates a four Hz square wave.The square wave and the four second timer are applied to the indicatorLED drivers 470 to flash the two indicator LEDs 310 a, 310 b (one isgreen and the other is amber, respectively) on and off simultaneously atfour Hz for four seconds. This action informs the user that the battery454 and indicator LEDs 310 a, 310 b are in working order. After the foursecond test phase, the system goes into its normal detection mode.

The detection mode uses the optical properties of stainless steel (thematerial encapsulating the radioactive isotope) and gold (the materialor plated material of the marker seeds) and the effects of red and bluelight on each stainless steel and gold seed. The optics of the systeminclude a blue LED 472 employing Gallium Nitride (GaN), a red LED 474employing Gallium Phosphide (GaP), a photosensor 476 including a photodiode and integrated amplifier, a GRIN (Graded Refractive Index) lens478, and a second photosensor 480, which are all housed within the blockmember 356 that houses the quartz sleeve 308. In FIG. 32A, the firstphotosensor 476 is perpendicularly oriented with respect to the quartzsleeve 308, and the blue and red LEDs 472, 474 are oriented also at anangle on either side of the first photosensor 476. Other orientations ofthe LEDs relative to the photosensor, and orientations of thephotosensor relative to the quartz housing, may be used to increase theaccuracy of the electronic detection circuit. Channels 482 within theblock member 356 direct light from the LEDs 472, 474 to a targetedlocation along the quartz sleeve 308 and also direct the reflected lightback to the first photosensor 476. The GRIN lens 478, positioned betweenthe quartz sleeve 308 and the first photosensor 476, focuses on thequartz lumen 308 a at the site where the distal gold marker shouldreside when all of the treating elements are within the quartz lumen308a. The GRIN lens 478 then collects light that is then directed ontothe surface of the photo diode.

The blue and red LEDs 472, 474 used in this system supply blue and redlight in restricted wavebands that peak at 450 nanometers (nm) and 700nanometers (nm), respectively. At 450 nm stainless steel (and tintedblue or untinted background) has greater than 90% reflectance and goldhas about 35% reflectances; at 700 nm both stainless steel and gold havegreater than 90% reflectance. This means that stainless steel reflectsblue and red light about equally well and gold reflects well in the redlight but poorly in the blue light (gold actually absorbs the bluelight). Therefore, the measurement of the blue/red ratio of reflectedlight can unambiguously distinguish between a gold-colored object, inthis case a gold marker, or some other object in the photosensor's fieldof view.

A clock oscillator 484 which oscillates at 3.22 kHz flashes the blue andred LEDs 472, 474 in turn (i.e., 180 degrees out of phase.) The clockoscillator 484 runs through a flip flop 486 where its frequency isdivided to create two signals, each having a frequency of 1.61 kHz. Oneof the two signals is applied to the blue LED driver 490 and the otheris applied to the red LED driver 492 so that each LED 472, 474 is drivenat approximately 1.61 kHz. Therefore, the on time and the off time ofthe blue and red LEDs 472, 474 are equal, as they take turns flashing onand off. The flashes of blue and red light travel from the LEDs 472,474, through channels 482 within the body, and through the quartz sleeve308 to the targeted location where the distal gold marker should be ifall of the seeds are within the quartz lumen 308 a. If a stainless steelseed is occupying the targeted location, then both the red and bluelight are reflected about equally well (greater than 90%). If nothingbut fluid or air fills the quartz lumen at the targeted location, thenthe background, as long as it is not tinted, also reflects both blue andred light similarly to that of stainless steel. If a gold marker seed iswithin the targeted location, then the red light is reflected but theblue light is absorbed. The first photosensor 476, consisting of a photodiode and a integrated amplifier, is optically coupled to the targetedlocation within the quartz sleeve 308 by the GRIN lens 478 so that thephotosensor 476 can measure the reflected quantities of each the blueand red lights. From this measurement, the blue/red ratio of reflectedlight is used to determine the presence or absence of a gold marker.

The viewing window 306 along the top 302 a of the transfer device 300allows ambient light to also be reflected off of the object within thefield of view of the photosensor 476. The photosensor 476 will mostlikely detect the ambient light in addition to the red and blue light.The signal of the ambient light may adversely affect the output of thephotosensor 476. The photosensor 476 must be operational even with lightcoming in through the transparent viewing window. Therefore, the signalsdue to ambient light sources must be removed from the system. This isdone by using a high pass filter 493 which is followed by synchronousdetector 494 followed by a low pass filter 496. The synchronous detector494 is a circuit which is synchronized with the blue and red LED pulses.The synchronous detector 494 removes all AC signals except for thoseattributable to the blue and red LEDs 472, 474. The low pass filter 496converts the AC (alternating current) output from the photosensor 476 toa DC (direct current) voltage because the system relies upon thedifferences between the red and blue signals. A blanking circuit is alsoincluded to isolate the low-pass filters for a brief period followingeach clock transition to improve the accuracy of the low-pass filteredsignals. The amplitudes of those signals correspond to how much light isbeing reflected from the targeted location and the DC voltage isproportional to the blue/red ratio of reflective light. The circuit isadjusted so that, in the case of gold being present at the targetedlocation, the DC voltage output is zero. In the case of any other objectpresent at the targeted location, the output is a non-null voltage.

The system is designed to produce a null voltage with the detection ofgold (and a non-zero voltage with the detection of stainless steel orbackground) because a null signal is unaffected by any gains encounteredalong the signal path (zero times any magnitude is always zero); thus,the null signal is much less likely to go outside the tolerance windowcreated around the reference voltage to be detected (null). Because thenull signal is less affected by variations within the system, such asmechanical tolerances and temperature changes, it is much more reliablethan a non-null voltage. The gold should produce the null because it isthe single state that must be distinguished from all others. The onlyadjustment needed for making the output voltage zero when a gold markeroccupies the targeted location is adjusting the intensity with which theblue LED 472 illuminates. Without that adjustment, stainless steel willproduce the null because it reflects the blue and red light equally andproduces signals close to the same amplitude when the intensity withwhich the blue and red LEDs 472, 474 illuminate are equal. Twoelectrical signals of the same amplitude produce zero volts. Conversely,because gold reflects red and absorbs blue when the blue and red LEDs472, 474 illuminate with the same intensity, the photosensor 476 sendsout signals of different amplitudes (high signal for red and low signalfor blue) which are converted to a non-null DC voltage. In order for thepresence of gold to produce a null, gold, not stainless steel, mustproduce equal amounts of reflection for both the blue and red lights.This is done by increasing the drive of the blue LED 472 relative to thedrive of the red LED 474 so that the blue LED 472 illuminates withgreater intensity than the red LED 474. Now gold equally reflects theblue and red lights which produces no AC signal from the photosensor476, thus, creating a null. On the other hand, the reflection ofstainless steel is brighter with the blue because of the boost given tothe blue LED driver 490. Therefore, the blue signal is larger than thered signal and the resulting square wave produces a non-zero DC voltage.To make sure the stainless steel treating elements and the backgroundalways produce a non-null output voltage, they should be untinted ortinted blue so as to reflect blue and absorb red which is the oppositeof what gold does.

When the DC signal is at zero volts, the system will indicate thedetection of gold. In practice, however, due to certain variationswithin the system, the DC signal will almost never read exactly zerovolts. Therefore, a window detector 498 with an upper limit referencevoltage and a lower limit reference voltage creates a band that iscentered on zero. The window detector 498 receives the DC signal anddetermines whether or not it lies within the set band (for example: −11to +11 millivolts). If the signal lies within the band, then the windowdetector decides that the signal is consistent with the presence ofgold. The width of the window can be changed in order to vary thetolerance of the system to errors (smaller width for tightertolerances). After the signal goes through the window detector, thedecoded signal enters the two drivers for the indicator LEDs 310 a, 310b. If the decoded signal indicates that gold is present, then the greenLED 310 a along the top 302 a of the transfer device 300 is illuminated,displaying to the user that all of the treating elements are within thequartz housing 308; and if the decoded signal indicates that gold is notpresent, then the amber LED 310 b along the top 302 a of the transferdevice 300 is illuminated, displaying to the user that not all of thetreating elements are within the quartz housing 308.

Both the blue and red LEDs 472, 474 are temperature sensitive and theiroutputs are affected by other factors, such as aging, level of currentdrive, and possibly ionizing radiation. In particular, the output of thered LED 474 significantly decreases as the temperature rises andsignificantly increases as the temperature drops. These temperatureinduced changes in the output of the red LED 474 will disturb theblue/red ratio of reflected light and may hinder the system's ability todetect the presence of gold. To stabilize the output of the red LED 474,a brightness control loop is included to regulate the output andcompensate for any temperature effects so as to hold the output of thered LED 474 constant. The blue LED 472, however, is sufficientlytemperature stable over the normal operating temperature range of +10°C. to +35° C. Therefore, no brightness control loop is necessary for theblue LED 472. The red LED brightness control loop incorporates thesecond photosensor 480. The second photosensor 480 compensates for thetemperature induced changes in the output of the red LED 474 by“staring” at the tip of the red LED 474 only and measuring how muchlight it is generating. To best measure the output, the secondphotosensor 480 is positioned at a 90° angle with respect to thelongitudinal axis of the red LED 474. The output signal of the red LED474 is detected in the same way as the blue/red reflective signal byflowing through the synchronous detector 500 a and high and low passfilters 502 c, 504 a. The outcoming signal then passes through theinverting DC amplifier 506 a which sets the control loop gain. Thesignal provides negative gain to the reference signal (RED_REF) 508 cthat sets the red LED drive range. The adjusted signal entering the redLED driver 492 attempts to maintain the output of the red LED 474constant even though the actual amount of light for any given currentmay be trying to change. This is a very simple control loop; otherarchitectures known to those skilled in the art may be used in itsplace. A control loop could be added to the blue LED also to improve thestability of its output.

Circuit diagrams corresponding to the logic diagram of FIG. 45 are shownin FIGS. 45A-C. FIG. 46B displays a one minute timer, a +5 power supplyand a −5 power supply. FIGS. 46C-1, C-2, and C-3 displays threecircuits: a +2.5 reference voltage; processes for the blue signal; andprocesses for the red signal. FIGS. 46A-1 and A-2 display two LEDcurrent drivers, a blanking circuit, a 3 kHz oscillator, a 4 kHz clock,a 4 second timer, a window detector and ± window threshold. Theseschematics display each component of the electronics and how theyinterrelate within the electronic system. A specific layout is shown.Other components or layouts which produce the same outcome may be used.The circuits are printed on boards 510 a, 512 a (FIG. 31) that aremounted to the chassis 304 of the transfer device 300.

As a backup to the electronic source detection system, the window 306above the quartz housing allows the user of the transfer device 300 tovisually detect whether or not all of the treating elements are withinthe quartz sleeve 308 by either detecting the presence of each markerseed on either side of the treating elements or by counting the numberof treating elements and marker seeds within the quartz sleeve 308. Toassist the user with visual detection, a magnifying lens 514 a (FIG.32A) is secured to the top portion of the body 302 a where it issituated directly above the quartz lumen 308 a. The magnifying lens 514a is also located above the indicator LEDs 310 a, 310 b so that they arealso magnified.

Turning to FIGS. 47-51C, there is seen a further improved transferdevice 500 of the catheter based radiation delivery system of thepresent invention. Similar to transfer device 300, transfer device 500has an exterior which is ergonomically designed to be easily handled bythe user and has internal components which include a pressure indicator,pressure relief valve, flow control valve and pathways, quartz housing,a catheter connector/pin gate interlock system, and a treatment elementelectronic detection system. The improved versions of these and othercomponents, as well as additional features incorporated into transferdevice 500 for additional safety and user feedback, are all described ingreater detail below.

As seen in the exploded view of FIG. 50, the exterior of the transferdevice 500 is made up of an upper portion 502 a and a lower portion 502b, each portion comprising a shell half. The two shell halves 502 a, 502b fit together to enclose a chassis 504, on which the components of thetransfer device 500 are mounted. Openings in the upper shell half 502 aallow user access to a power button 506 for activating the electronicdetection system and indicator lights 508 a, 508 b, and a fluid controlswitch 510 for activating the fluid control valve 512 (FIG. 47). Theupper shell portion 502 a also includes a pressure indicator window 514,and a magnifying window 516 for viewing the indicator lights 508 a and508 b, the quartz sleeve 518 where the treatment elements and markerseeds are stored, and the distal passageways 523 leading from the quartzsleeve 518 to the distal opening 524 of the transfer device 500. The twoshell halves 508 a and 508 b together create openings along the sides ofthe transfer device 500 that allow access to a fluid entry port 526, asliding gate actuator switch 528 and either end of a latch mechanism 586for the catheter connector. Together, the two shell halves 508 a and 508b also create an opening 524 (FIG. 49) at the distal end of the transferdevice 500 for entry of the catheter connector and an opening at theproximal end of the transfer device 500 allowing access to a fluid exitport 530, which preferably does not extend much, if at all, beyond theexterior wall of the transfer device 500. A compartment for storing afluid collection bag (described in relation with transfer device 300)may be eliminated to create space inside the transfer device 500 forinternal components. Instead a clip may be added to the bottom of thetransfer device 500 to secure a fluid collection bag (not shown).Polyurethane is an example of a material that can be used to make thetwo shell halves 508 a and 508 b.

The transfer device 500 has a fluid entry.port 526 to which a source ofpressurized fluid (liquid or gas), such as a fluid filled syringe orautomatic fluid pump, is connected for hydraulic or pneumatic deliveryand retrieval of treatment elements. The fluid entry port 526 as shownin FIG. 51A has a luer connector. Two offset arms 532 a and 532 bsimilar to support arms 326 a, 326 b described above in connection withtransfer device 300 extend from the shell portions 502 a and 502 b tosupport and orient a syringe 534 a along side transfer device 500 atpredetermined angles with respect to its longitudinal axis to affordeasier manipulation of the syringe plunger 534 b and proper alignmentbetween the distal end of the syringe 534 a and the fluid entry port526. As depicted in FIG. 48, the syringe 534 a is angled outwardlyapproximately seven degrees and upwardly approximately twenty-fivedegrees with respect to the longitudinal plane of the transfer device500. The support arms 532 a and 532 b (FIGS. 47 and 49) are configuredsuch that the arm 532 a extending from the upper shell portion isproximal to the arm 532 b of the lower shell portion, thus providing aclearer site line between the proximal end of the transfer device 500and the fluid access 526 port for quick and easy connection of thesyringe 534 a.

With reference to FIGS. 50-51B and 52, the chassis of transfer device500 also supports a pressure indicator 536 and a pressure relief valve538 that work independently from one another. The pressure indicator 536assists the user in determining the appropriate pressures necessary tosend and retrieve treatment elements to and from the distal end of thecatheter and to maintain the treatment elements at the distal end of thecatheter during treatment. The pressure relief valve 538 preventsoverpressurization of the system which could damage the catheter and/orthe transfer device 500.

The pressure indicator 536 comprises a hollow cylinder 540 having aninlet port 542 in fluid communication with the fluid source at one endand an end plug 544 at the other end. The cylinder 540 houses a piston546 and a compression spring 548 residing between the piston 546 and theend plug 544. The piston 546 may be a ring seal as described above inconnection with transfer device 300, a rubber plunger obtained from asyringe, or a piston of a harder material with o-ring groovesaccommodating o-rings such that they create a seal with the cylinderinside wall. The spring 548 is preferably stainless steel, such as aspring having part number C0300-032-18 manufactured by Mid-West ExpressCompany. The compression spring 548 used must have a spring rate (i.e.,the amount of deflection per unit force) that biases the piston 546 to aspecific position along the pressure indicator window 514 for the systemoperating pressures (0 to 100±15 psi). The pressure inside the transferdevice 500, created by the fluid source, moves the piston 546 in thecylinder 540 such that it compresses the spring 548 and forces the airon the other side of the piston to escape through a vent opening in theend plug 544. The seal created by the piston 546 about the periphery ofthe cylinder's inside wall keeps the fluid from passing by the piston546. As seen in FIG. 47, the piston 546 accommodates a piston ring 550which is highly visible through the pressure indicator window 514. Thepiston ring 550 not only serves as the pressure marker but also providessome rigidity along the central portion of the piston 546. Additionally,a background material may be provided along the bottom of the cylinder540 so as to block the view of other components which may interfere withthe visibility of the piston 546 and piston ring 550. However, otherstandard pressure gauges may be used in place of the spring-loadedpiston and cylinder arrangements described above.

Lettering and/or markings 554 are placed on the exterior of the transferdevice 500 next to the pressure indicator window 514 to indicate wherethe piston ring 550 should reside within the pressure indicator window514 to provide the appropriate pressure for transferring the treatmentelements to and from the catheter and to indicate where the piston ring550 should reside to provide the appropriate pressure for maintainingthe treatment elements at the distal end of the catheter for theduration of the treatment. The pressure for maintaining the treatmentelements at the distal end of the catheter is much less than thepressure required to quickly send and retrieve the treatment elements.Both the pressure indicator 536 and the pressure relief valve 538 areretained by an L-shaped block portion 556 that is mounted to the chassis504.

The pressure relief valve 538 is a standard valve with an activationpressure of 100±15 psi. Such a valve is that having part numberPCRM0000001S, manufactured by The Lee Company of Westbrook, Conn. Thepressure relief valve 538 comprises a pin, a ball, a spring, and aspring retainer and is press fitted into a pressure relief valve housing558. Each end of the pressure relief housing 558 mates with a fluidconnector 559 System pressure above 100±15 psi is forceful enough tounseat the spring biased ball and allow the fluid to flow through thevalve 538 and exit the transfer device 500 through the fluid exit port530 into an external fluid reservoir (not shown). Otherwise, the springbiases the ball into a seated position thereby blocking flow through thevalve 538 and allowing flow to continue to be safely directed throughthe system.

The appearance and functionality of fluid control valve 512 areidentical to that of fluid control valve 330 in FIG. 31. The fluidcontrol valve 512 of the present transfer device 500 directs the fluidflow of the system which can be manipulated by toggling the flow controlswitch 510 between detented send, return, and neutral positions. Thevalve 512 may comprise four ports 562 and should be capable ofwithstanding the system's highest operating pressure (i.e. at least 100to 115 psi), such as valve part no. 0162336 (HV4-4, w/0.040 ports),manufactured by the Hamilton Company of Reno, Nev.

As indicated above, the interior components of the transfer device 500are constructed separately and mounted to the chassis, where they arejoined together for fluid communication by means of tubing (not shown)and barbed connectors, such as 542 shown in FIG. 52. FIG. 53 is a flowcontrol diagram that visually explains fluid flow of the system.

Turning to FIGS. 48 and 50-51C, the transfer device 500 further includesa separate block member 564 which is mounted to the chassis 504 andhouses the quartz sleeve 518, a pin gate mechanism 576, and the opticsportion of a seed verification system. As an improvement to the blockmember 564 described earlier in connection with transfer device 300, thepresent block member 564 has a mated projection 566 that is machinedbelow the surface of the block member 564 such that it is recessedwithin a cavity 568. This simplified design reduces the number ofcomponents by allowing an o-ring groove 570 to be cut directly into theblock member cavity 568 wall surrounding the mated projection 566.

The block member 564 may contain a spring loaded assembly (not shown) tohold the quartz sleeve 518 in its proper position (in alignment with theoptics for proper seed detection) even when the transfer device 500 isdropped. A lumen 572 extends along the length of the quartz sleeve 518for storage of the treatment elements and marker seeds when they are notbeing used to deliver radiation therapy. The quartz sleeve 518 shieldsthe user from beta particles emitted by the treatment elements whenstored therein, thus enabling a user to safely handle the transferdevice 500. The distal end of the quartz lumen 572 preferably has achamfer to prevent seed hang-ups when transferring them. As describedpreviously, the entire length of the quartz sleeve 518 can be seenthrough an opening in the block member 564 which is aligned with theviewing window 516. To provide better visibility of the treatmentelements and marker seeds within the quartz sleeve 518, a coloredmaterial (preferably white) may be adhered to or placed under the bottomof the quartz sleeve.

The pin gate mechanism 576 consists of a pin gate 578 a, cylindrical pinhead 578 b, slider block 580, pivoting lock 582, leaf spring 584 a, andleaf spring block 584 b all working together to position the pin gate578 a in an extended (closed) or retracted (open) position relative tothe lumen 523 just distal of the quartz sleeve 518 for respectivelyblocking or permitting passage of treatment elements. The components andfunctions of the pin gate mechanism 576 are identical to that of pingate mechanism 352 described above in connection with transfer device300. However, the pin gate mechanism 576 of the present inventionprovides an additional safety feature for preventing the pin gate 578 afrom closing onto and damaging a treatment element. If an attempt toclose the pin gate 578 a is made while a treatment element is in thepathway of the pin gate 578 a, the pivoting lock 582 is oriented in sucha way that it does not clear the pathway of the moving slider andprevents any further advancement of the slider, which in turn halts thedownward motion of the pin onto the treatment element. Additionally, thepin gate mechanism 576 may be positioned such that the pin gate 578 a isextended and retracted into the distal end of the quartz lumen 572through a radial channel extending from the top of the quartz sleeve 518and intersecting with the quartz lumen 572.

In place of a release trigger/release switch mechanism 350 (shown inFIG. 38), the present transfer device 500 includes a latch mechanism 586(shown in FIGS. 48, 51A, and 54A-56C) for receiving, locking, andproperly seating the catheter connector in the transfer device. Thecomponents of the latch mechanism 586 include a latch body 590, a latchsear 592, a latch button 594, and two ball and spring plungers 596, allof which reside in between the block member 564 and end body 598 of thetransfer device 500. As illustrated in FIGS. 54A-B and 56B, the latchbody 590 is generally rectangular with an elongated opening as seen fromits distal face and a raised portion with a U-shaped recess as seen onits proximal face. The U-shaped recess is adjacent to the elongatedopening, extends partially along the opening's length, and is accessibletherethrough. Because the U-shaped recess is smaller than the elongatedopening, some of the raised U-shaped portion 600 surrounding the recessoverlaps a portion of the elongated opening. The latch body 590 ispreferably made from an opaque material (such as Delrin) to providelubricity between it and the polycarbonate pieces (i.e. block portion564 and end body 598) with which it will be in sliding contact. Thelatch sear 592 (FIGS. 55 and 56B-C) fits within a similarly shapedrecessed portion along the proximal face of the latch body 590 such thatthe small end 606 of the latch sear 592 extends within the elongatedopening (FIG. 56B). The latch button 594 houses a compression spring 608and slides over the upper ends 610 and 612 of the latch sear 592 andlatch body 590 such that the latch sear 592 and compression spring 608are in contact with one another and the latch button 594 is secured tothe latch body 590. The ball and spring plungers 596 (FIG. 50) extendfrom shallow bores within the end body 598 such that each of the twoballs rests within one of the valleys 614 along the proximal face of thelatch body 590 in between the elongated opening and the extended portionwith the through hole.

As a catheter connector 588 is being inserted into the transfer device500, the distal end of the connector 588 passes through the unobstructedhalf of the elongated opening of the latch body 590 and seats itself onthe mated projection 566 extending from the block member 564 (FIGS.51A-B). To lock the connector 588 into the transfer device 500, thelatch button 594 is pressed inward to facilitate engagement of therelieved section of the connector 588 with the U-shaped portion 600 thatoverlaps the elongated opening in the latch body 590. As the latch body590 is moved from the unlatched position to the latched position, theball of each of the two ball and spring plungers 596 is ramped onto oneof the peaks 616 adjacent the valleys 614 on the proximal face of thelatch body. This ramping causes the spring biased plungers 596 tocompress and force the latch body 590 and engaged connector 588 towardthe mated projection 566 at the distal end of the block member 664;thus, ensuring that the chamfer 618 of the connector insert 632 iscompletely seated against the projection 566 and in complete alignmentwith its opening. As an indication that the connector 588 has been fullyengaged, the free end 620 of the latch body 590 (opposite that endconnected to the latch button 594) pops out from the side of thetransfer device 500 (FIGS. 47, 48, and 51A). If a band 622 or othermarking on the free end 620 is fully visible, then the user can be surethat the connector 588 is now locked into the transfer device 500. Todisengage the connector 588 from the transfer device 500, the free end620 of the latch body 590 is pushed inward to remove the U-shapedportion from the relieved area of the connector 588.

To provide a safer transfer device, an interlock mechanism existsbetween the latch body 590 and the slider block 580 as can be seen inFIGS. 48 and 51A . The slider block 580 slides toward the distal end ofthe transfer device 500 to retract the pin gate 578 a and thus, allowthe treatment elements to be delivered out of the transfer device 500.To enable this movement, the shaft 581 extending from the distal end ofthe slider block 580 and the through holes of the latch button 594,latch sear 592, and latch body 590 must all be in alignment. When thelatching mechanism 586 is in the unlatched position, regardless ofwhether or not a connector 588 is inserted into the transfer device 500,the extending shaft 581 does not align with the through holes andadditionally, the actuator switch 528 is impeded by the popped up latchbutton 594. When the latching mechanism 586 is in the latched positionand no connector 588 is locked into the transfer device 500, the throughhole in the latch sear 592 does not completely align with the throughhole in the latch button 594 and movement of the slider block 580 isimpeded by the latch sear 592. However, when the connector 588 isinserted into the transfer device 500 and the latch body 590 is slidtoward the connector 588 for engagement purposes, the small end 606 oflatch sear 592 collides with the connector 588 just above theconnector's relieved portion 589 and is forced toward the latch button594 and against the spring 608 such that the sear's through hole nowaligns with both the latch body through hole and the latch buttonthrough hole. Thus, the pin gate 578 a can only be retracted to an opengate position when the connector 588 is inserted into the transferdevice 500 and fully engaged by the latching mechanism 586. Furthermore,when the necessary conditions are met and the shaft 581 extends throughall three holes as seen in FIG. 51A, the latch body 590 cannot be slidback to the unlatched position, thus preventing the latch body 590 fromdisengaging the relieved portion 589 on the connector 588. As an extrasafety caution and a visual reminder to the user that the connector 588is not to be disengaged from the transfer device 500 while the pin gate578 a is in a retracted position, the actuator switch 528 is configuredto at least partially cover the latch button 594, thus preventing thelatch body 590 from being moved into the unlatched position.

Turning to FIGS. 57A-58A and 57C, the catheter connector 588, which is apart of the present invention, is provided with detents 626 thatinterlock with an annular shoulder in the end body 598 of the transferdevice 500 and must be manually actuated to withdraw the catheterconnector 588 from the transfer device 500 after it has been unlatchedby the latching mechanism 586. The catheter connector 588 includes acentral plug portion 630 having a through lumen 630 and cantilever arms634, a connector insert 632 which is received by central plug throughlumen 630, and a skirt 636 that fits over the distal portion of theconnector 588 that remains outside of the transfer device 500 when theconnector 588 is fully connected thereto. The connector insert 632 isidentical to the connector insert 390 described above and shown in FIGS.41E and D. The central plug portion 628 may be identical to the onedescribed above and shown in FIGS. 4C and D or may be slightly differentby having the wall between the two-o-rings taper inward from both endsto enhance the sealing effects of the o-rings. The skirt 636 57A-(FIGS.57A-B and 58A) is threaded over the catheter tubing and then after theconnector 588 is bonded to the catheter tubing, it is fitted over adistal portion of the connector 588 which includes the cantilever arms634. When the connector 588 is fully inserted into the transfer device500, the skirt 636 covers the slotted portions 642 that remain externalto the transfer device 500, abuts the distal tip of the transfer device500, and surrounds the connector entrance 524 to the transfer device500. These characteristics of the skirt 636 serve to maintain sterilityof the distal portion of the connector 588 as well as prevent foreignmatter from contacting the connector entrance to the transfer device 500through the slotted portions 642 of the central plug 630. As shown inFIG. 57A, the skirt 636 preferably has two opposing rectangular sides645 for mating with the depressable sides of the cantilever arms 634 andfor indicating to the user where to manipulate the cantilever arms 634.The skirt 636 is preferably made of silicone or other material that isflexible enough to permit manipulation of the cantilever arms 636 as theconnector 588 is pulled out of the transfer device 500. In addition, therectangular sides 645 may be thinner than the rest of skirt 636 so as toprovide for easier manipulation of the cantilever arms 634. Having todepress the arms 634 while simultaneously pulling on the connector 588is another safety feature for preventing inadvertent withdrawal of theconnector 588 from the transfer device 500.

As, seen in FIG. 58A, catheter 647 of the present invention connects tothe transfer device 300, 500 by catheter connector 588 to permitdelivery of the treatment elements to a selected site within a patient.With reference to FIGS. 58A-C, the catheter 647 and its components(except for the catheter connector as described just previously) areidentical to that shown in FIGS. 42A-42D. However, the most distalmarker band of the present invention is in closer proximity to theproximal end of the intraluminal connector 646 the intraluminalconnector 646 at the distal end of the catheter 647 may be made ofplatinum/iridium so as to be visible under fluoroscopy and possiblyeliminate the need for the distal marker band 652. Also, the catheterfluid lumens 648 and 650 (especially the fluid return lumen 650) shallhave dimensions suitable for transmitting hydraulic or pneumaticpressure for movement of the treatment elements within three to tenseconds are preferably dimensioned to provide treatment element send andreturn times each in the range of three to ten seconds and morepreferably within two to six seconds, while not exceeding a 5 Frenchouter catheter diameter, not exceeding a pressure of 100 psi, and usingless than 20 cc of fluid to send, maintain, and return the treatmentelements.

The treatment elements 658 are preferably radioactive sources asdescribed within application Ser. No. 08/628,231, filed Apr. 4, 1996,and incorporated herein by reference. The treatment elements 658 consistof twelve radioactive cylinders 660 in series and two marker seeds 659 aand 659 b, one at each end of the radioactive train. The marker seeds659 a and 659 b are used to properly position the treatment elements 658at the treatment site and are preferably gold or gold plated since goldis visible under fluoroscopy, which is used to monitor the radiationdelivery. To decrease the source train delivery time to and retrievaltime from the distal end of the catheter, the ends of the marker seeds659 may be slotted or marker seeds can be of gold tubing filled withepoxy. Most preferably, the distal end of the distal marker seed 659 isslotted to prevent it from blocking the opening to the intraluminalconnector 646 and the proximal end of the proximal marker seed 659 isslotted.

In addition to the radiation doses described in the above referencedapplication Ser. No. 08/628,231, a therapeutic radiation dose of 14 Gyat 2 mm in vessels of approximately 2.7 to approximately 3.2 mm indiameter or of 18 Gy at 2 mm in vessels of approximately 3.2 toapproximately 4.0 mm in diameter may be administered to the patient.

At specific times during the radiation therapy procedure, it may benecessary or desirable to determine the position of the treatingelements 658 and marker seeds 659 with respect to the quartz sleeve 518in the transfer device 500. For example, the user may need to verifythat all twelve treating elements 658 and two marker seeds 659 arepresent within the quartz sleeve 518 before delivery of the elements tothe distal end of the catheter 647, and for safety reasons must be surethat all of the treating elements 658 and marker seeds 659 are withinthe quartz sleeve 518 prior to closing the gate 578 a and disconnectingthe catheter 647 from the transfer device 500.

To determine whether or not all of the treatment elements 658 are withinthe quartz sleeve 518, an electronic detection system, which measuresthe presence or non-presence of the distal gold marker seed 659 at asingle position within the quartz lumen 572, is included in the transferdevice 500. This electronic detection system functions similarly to thepreviously described detection system to determine and indicate whetheror not the treatment elements 658 are within the quartz sleeve 518.However, the means employed by the electronic detection to achieve theend result is altered slightly to produce a simpler, more efficientsystem, and a more accurate reading of the location of the treatmentelements 658 and marker seeds 659 a and 659 b.

The system detects a gold marker calorimetrically by shining light ofdifferent wavelengths onto the small area where the gold marker shouldreside within the quartz housing 518 and then measuring thereflectivity. Based on the way reflectivity varies with wavelength, thesystem determines whether a gold object (gold marker) or non-gold object(stainless steel seed, background, or saline filled quartz lumen) isoccupying the area. If a gold marker seed is detected, it would bereasonable to conclude with a safe degree of certainty that it is thedistal marker seed 659 b and that all of the elements proximal to thedistal marker seed 659 b are also within the quartz housing. To increasethe degree of certainty that all seeds are within the quartz housing518, the electronic sensor can be made to determine whether both markerseeds 659 a and 659 b are properly positioned within the quartz housing518. However, this will require more space within the transfer devicehousing for additional electronic and optical components.

In practice, photosensors are not equally sensitive to blue and redlight and the intensity of one or the other must be adjusted by a fixedcompensation factor to achieve the condition where the photosensorelectrical output is the same for both colors. This technique is wellknown to those well versed to opto-electronics, and it will be assumedin the rest of this description that where it is stated that the red andblue intensities are equal, it is meant that they are equal as measuredby the output of the photosensor.

In addition to detecting the absence or presence of a gold marker at aspecific position in the quartz sleeve lumen 572, the electronics waitin a low power state for the power button 506 to be pressed, then flashtwo indicator Light-Emitting Diodes (LEDs) 508 a and 508 b on and offfor about 4.7 seconds after the power button 506 has been pressed toindicate that the LEDs 508 a and 508 b and batteries 664 are functional,indicate whether a gold marker is detected by illuminating one of twoindicator LEDs 508 a and 508 b, and finally automatically return to thelow power state after five minutes has elapsed to conserve the batterypower, or restart the five minute timing period if the button 506 ispressed again during those five minutes.

The electronic system is powered by a 6v battery pack 664 which containstwo 3v lithium cells used in series to produce +6v. The output is alsoinverted to produce a −6v supply required by the electronic circuitry.Examples of such batteries include Sanyo CR-P2, Panasonic CR-P2, andDuracell DL223A batteries. For safety precautions, a fuse is in serieswith the battery. When necessary, the upper shell half 502 a of thetransfer device can be removed to replace the battery pack.

The power supply is controlled by a sleep circuit. Applying power turnsthe sleep circuit off, which in turn shuts down the power supply so thatit draws only enough power to keep the system alive. The on-switch 666is a single pole double throw (SPDT) push button switch 506. When theswitch 666 is closed by momentarily pressing the button 506 from theexterior of the transfer device 500, the sleep circuit is awakened andturns on the power supplies 668,670, one generating +5v and the othergenerating −5v. The power generated is first applied by starting thecountdown of an internal timer (a counter driven by 27.3 Hz) 672 set forfive minutes. At the end of five minutes the power supplies 668, 670 areturned off and the sleep circuit becomes inactive until the next timethe switch 666 is closed. If the button 506 is pressed during the fiveminute timing period, the timing period is reset allowing the power tostay on longer than five minutes. The internal timer 672 can be set forone of several durations in the existing in the existing design. Eachtime the five minute timer 672 is started, a 4.7 second test phase 674also begins and enables a 3.4 Hz oscillator 676 which is derived from a3.5 kHz oscillator 690. The 3.4 Hz oscillator 676 and the 4.7 secondtime 674 are applied to the indicator LED drivers 677 to flash the twoindicator LEDs 508 a and 508 b (one is green and the other is amber) onand off simultaneously at 3.4 Hz for 4.7 seconds. This action informsthe user that the batteries 664 and indicator LEDs 508 a and 508 b arein working order. After the 4.7 second test phase 674, the system goesinto its normal detection mode.

The detection mode uses the optical properties of stainless steel (thematerial encapsulating the radioactive isotope) and gold (the materialor plated material of the marker seeds) and the resulting differentreflectivity's of red and blue light on each stainless steel and gold.The optics of the system include a blue LED 678 employing GalliumNitride (GaN), a red LED 680 employing Gallium Phosphide (GaP), aphotosensor 682 including a photo diode and integrated amplifier, a GRIN(Gradient Index) lens 684, and a second photosensor 686, which are allhoused within the block member 564 that houses the quartz 518. In FIG.51C the first photosensor 682 is perpendicularly oriented with respectto the quartz sleeve 518 , and the blue and red LEDs 678, 680 areoriented at an angle on either side of the first photosensor 686.Channels 688 within the body direct light from the LEDs 678,680 to atargeted location along the quartz sleeve 518 and also direct thereflected light back to the first photosensor 682. The GRIN lens 684,positioned between the quartz sleeve 518 and the first photosensor 682,focuses on the quartz lumen 572 at the site where the distal gold marker659 b should reside when all of the treating elements 518 are within thequartz sleeve 518. The GRIN lens 684 then produces an image that becomesroughly focused onto the surface of the photodiode. The axes of the GRINlens, the red and blue LEDs, and the first photosensor must allintersect at or very near the same point along the axis of the quartzhousing 518 to reliably determine the presence or non-presence of a goldmarker seed.

The blue and red LEDs 678, 680 used in this system supply blue and redlight at peak wavelengths of 450 nanometers (nm) and 700 nanometers (nm)respectively. At 450 nm stainless steel has more than 90% reflectanceand gold has about 35% reflectance; at 700 nm both stainless steel andgold have more than 90% reflectance. This means that stainless steelreflects blue and red light about equally well and gold reflects well inthe red light but poorly in the blue light (gold actually absorbs theblue light). Therefore, the measurement of the blue/red ratio ofreflected light can unambiguously determine whether or not a goldcolored object, in this case a gold marker, is in the photosensor'sfield of view.

An analog clock oscillator 690 which oscillates at 3.5 kHz runs througha flip flop 692 where its frequency is divided by two to create twosignals, each having a frequency of 1.75 kHz, to flash the blue and redLEDs 678, 680 in turn (180 degrees out of phase). One of the two signalsis applied to the blue LED driver 694 and the other is applied to thered LED driver 696 so that each LED 678,680 is driven at approximately1.75 kHz. Therefore, the on time and the off time of the blue and redLEDs 678,680 are equal as they take turns flashing on and off. Theflashes of blue and red light travel from the LEDs 678, 680, throughchannels 688 within the block member 564, and through the quartz 518 tothe targeted location where the distal gold marker should be if all ofthe seeds are within the quartz lumen 572. If a stainless steel seed orfluid is occupying the targeted location, then both the red and bluelight are reflected equally well (approximately 96%). If nothing fillsthe quartz lumen 572 at the targeted location, then the background, aslong as it is untinted, also reflects both blue and red light similarlyto that of stainless steel. If a gold marker seed is within the targetedlocation, then the red light is reflected but much of the blue light isabsorbed. A first photosensor 682, consisting of a photo diode and anintegrated amplifier, is optically coupled to the targeted locationwithin the quartz 518 by the GRIN lens 684 so that the photosensor 682can measure the reflectivity in each the blue and red light. From themeasured reflectivities, the blue/red ratio of reflected light is usedto determine the presence or absence of a gold marker.

The viewing window 516 along the top 502 a of the transfer device 500allows ambient light to also be reflected off of the object within thefield of view of the photosensor 682. The photosensor 682 will detectthe ambient light in addition to the red and blue light. The signal ofthe ambient light superimposed on the signal of each the blue and redLEDs 678, 680 may affect the output of the photosensor 682. Thephotosensor 682 must be operational with light coming in through thetransparent viewing window 516; therefore, the signals due to ambientsources must be removed from the system. This is done by using in seriesa high-pass filter 698, a buffer 700, a synchronous detector 702 and alow pass filter 704. The high-pass filter removes all DC (directcurrent) light signals (e.g. daylight or flashlight); the buffer helpsthe synchronous detector to reduce background noise by providing a lowimpedance drive. The synchronous detector is a circuit which issynchronized with the blue and red LED pulses. The synchronous detectorprocesses the blue and red signals using the same 1.75 kHz oscillatorused to drive the blue LED 678 and removes all signals except for thoseattributable to the blue and red LEDs 680 and converts the resulting ACsignal to a DC signal. The amplitude of each pulse corresponds to howmuch light is being reflected from the targeted location and the DCvoltage is inversely proportional to the blue/red ratio of reflectedlight. In the case of gold being present at the targeted location, theDC voltage output is nominally zero. In the case of any other colorpresent at the targeted location, the output is a non-null voltage. Thelast step in filtering out signals from ambient light is using a lowpass filter to remove the ripple on the DC signal exiting thesynchronous detector.

The system is designed to produce a nominally null voltage with thedetection of gold (and a positive non-zero voltage with the detection ofstainless steel or background) because a null signal is unaffected byany gains encountered along the signal path (zero times any magnitude isalways zero); thus, the null signal is much less likely to go outsidethe tolerance window created around the reference voltage to be detected(null). Because the null signal is less affected by variations withinthe system, such as mechanical tolerances and temperature changes, it ismore reliable than a non-null voltage. After setting the red LED, theonly adjustment needed for making the output voltage zero when a goldmarker occupies the targeted location is adjusting the intensity withwhich the blue LED 678 illuminates. Two signals of the same amplitudeproduce zero volts AC. Conversely, because gold reflects red and absorbsblue when the blue and red LEDs 678, 680 illuminate with the sameintensity, the photosensor 682 sends out signals of different amplitudes(high signal for blue and low signal for bred) which are converted intoa non-null DC voltage. In order for the presence of gold to produce anull, gold, not stainless steel, must produce equal amounts ofreflection for both the blue and red light. This is done by increasingthe drive of the blue LED 678 while maintaining the drive of the red LED680 constant so that the blue LED 678 illuminates with greater intensitythan the red LED 680. The amount by which the drive must be increased isthat which produces equal amplitudes for both red and blue reflectedlight. By increasing the intensity of the blue light by a specificpercentage, gold now reflects the blue light equally as well as the redin comparison to absorbing the blue when the red and blue LEDs 680, 678have the same drive. Now gold reflects equal amounts of the blue and redlight which produces no AC signal from the photosensor 682, thus,creating a null. On the other hand, the reflection of stainless steel isbrighter with blue because of the boost given to the blue LED driver694; therefore, the blue signal is larger than the red signal and theresulting square wave produces a non-zero DC voltage. To make sure thestainless steel treating elements and the background always produce anon-null output voltage, they should be untinted or tinted blue so as toreflect blue and absorb red, which is the opposite of what gold does.

When the DC signal is at nominally zero volts, the system will indicatethe detection of gold. In practice, however, due to certain variationswithin the system, the DC signal will rarely read as zero volts. Apositive threshold detector 706 is included in the system to compare thethreshold reference voltage with the filtered and rectified DC signal (atrue window detector with both positive and negative thresholds centeredaround zero is not necessary because signals from the stainless steelseeds, saline, and quartz lumen are found to always be positive). Thebuffered +2.5 v reference voltage 708 travels through a potentialdivider 710, followed by a unity gain buffer 712 to generate thethreshold reference voltage WIN+ 714. The threshold detector 706receives the DC signal and determines whether or not it exceeds thepositive threshold(for example, +450 millivolts). If the signal does notexceed the threshold, then the threshold detector 706 decides that thesignal is consistent with the presence of gold. The threshold can bechanged in order to vary the tolerance of the system to errors. Afterthe signal goes through the threshold detector 706, the decoded signalenters the two drivers for the indicator LEDs 508 a and 508 b. If thedecoded signal indicates that gold is present, then the green LED 508 aalong the top 502 a of the transfer device 500 within the quartzretainer 730 is illuminated, displaying to the user that all of thetreating elements are within the quartz housing 518. If the decodedsignal indicates that gold is not present, then the amber LED 508 balong the top 502 a of the transfer device 500 within the quartzretainer 730 is illuminated, displaying to the user that possibly notall of the treating elements are within the quartz housing 518.

Both the blue and red LEDS 678, 680 are temperature sensitive. The redLED output significantly decreases as the temperature rises andsignificantly increases as the temperature drops. These temperatureinduced changes in the red LED output will disturb the blue/red ratio ofreflected light and may hinder the system's ability to detect thepresence of gold. To stabilize the red LED output, a brightness controlloop is included to regulate the output and compensate for anytemperature effects so as to hold the red LED output constant. The blueLED 678, however, is sufficiently temperature stable over the normaloperating temperature range of +10° C. to +35° C.; therefore, nobrightness control loop is necessary for the blue LED 678. The red LEDbrightness control loop incorporates a second photosensor 686. Thesecond photosensor 686 compensates for the temperature induced changesin the LED output by “staring” at the tip of the red LED 680 only andmeasuring how much light it is generating. The second photosensor 686 ispositioned at a 90° angle with respect to the longitudinal axis of thered LED 680. The red LED output signal is detected in the same way asthe blue/red reflective signal by flowing through a high-pass filter716, buffer 718, synchronous detector 720 and a low pass filter 722. Theoutcoming DC signal then passes through the noninverting DC amplifier724 to set the control loop gain 726. The signal adds either a positiveor negative gain to the reference signal (RED-REF) 727 that sets the redLED drive range. The adjusted signal entering the red LED drivermaintains the red LED output constant even though the actual amount oflight for any given current may vary.

A block diagram of the electronics used to calorimetrically detect thedistal gold marker 659 b is shown is FIG. 60. The electronics are builtonto two printed circuit boards, PCB A and PCB B. These printed circuitboards can be seen in FIGS. 62A and 62B. For testing procedures each PCBhas a test connector which makes accessible signals and voltages withinthe circuit. The PCB's are stored within a plastic bag for protectionagainst moisture and mounted on the under side of the chassis within thetransfer device. The schematic diagrams of the electronics on PCB A areshown in FIGS. 61A-B and the schematic diagram of the electronics on PCBB is shown in FIGS. 61C-1 and C-2. FIG. 61D is a schematic of thedistribution board which is housed on top of the battery pack 664 andFIG. 62C shows the mechanical outline of the distribution board. Theelectrical connections between the different parts of the detectionsystem are shown in FIG. 63A and an equivalent circuit for the circuitryshown in FIG. 63A in addition to showing how the connections are routedthrough the distribution printed circuit board and the micro printedcircuit boards which are mounted on the two photosensors 682 and 686.

As a backup to the electronic source detection system, a window 516above the quartz housing 518 allows the user of the transfer device 500to visually detect whether or not all of the treating elements 658 arewithin the quartz housing 518 by either detecting the presence of eachmarker seed 659 a and 659 b on either side of the treating elements orby counting the number of treating elements 658 and marker seeds 659within the quartz housing 518. To assist the user with visual 5detection, a magnifying lens 728, as shown in FIGS. 48, 50, and 51C, issecured to the top portion of the block portion 564 where it is situateddirectly above the quartz lumen 572. The magnifying lens 728 is alsosupported by the quartz retainer 730; therefore, the indicator LEDs 508a and 508 b are also magnified. The lens used may magnify in one or twodimensions and may have an order of magnification of 2× or greater. Thelens is a cylindrical glass lens of plano-convex form. However, otherlenses may be used.

Although the above inventions has been described in terms of certainspecific embodiments, it is understood that various changes andmodifications may be made without departing from these inventions andreference should be made to the appended claims to determine the properscope of these inventions.

What is claimed is:
 1. In a system used for the intraluminal treatmentof a selected site in the body including a catheter adapted forintraluminal positioning in the body and a transfer device external tothe body for storing one or more treating elements and introducing thetreating elements into the catheter, a method for detecting whether thetreating elements reside within the transfer device comprising:encapsulating the treating elements in a material having knownreflectivity characteristics; shining first and second lights ofdifferent wavelengths and having known reflected intensities into anarea in the transfer device where the treating elements are storedbefore and after being introduced into the catheter; measuring thereflected intensities of the first and second lights reflected off ofthe area in the transfer device; forming a ratio of the reflectedintensities of the reflected first and second lights; comparing theratio of the reflected intensities of the reflected first and secondlights with the known reflectivity characteristics of the encapsulatingmaterial for the treating elements; determining whether the measuredratio of reflected intensities is substantially the same as the knownreflectivity characteristics; and indicating whether the treatingelements reside within the transfer device.
 2. The method of claim 1wherein said first and second lights are flashed in turn onto an area ofthe transfer device where the treating elements are stored.
 3. Themethod of claim 1 further comprising: assembling said treating elementsin a linear array, said treating elements being encapsulated instainless steel; placing a marker element at at least one end of saidlinear array of treating elements, said marker element beingencapsulated in gold; and shining said first and second lights onto thearea in the transfer device where the marker element is stored beforeand after the treating elements are introduced into the catheter, saidfirst light being blue and said second light being red.
 4. The method ofclaim 3 further comprising: creating signals corresponding to thereflected intensities of the lights reflected off the area in thetransfer device; filtering out any signals created by ambient light; andcomparing the signals created by said first and second reflected lightsto signals corresponding to the known reflectivity characteristics ofthe encapsulating material at different wavelengths.
 5. The method ofclaim 4 further comprising: creating a signal having a null outputvoltage for the lights reflected off said marker element.
 6. The methodof claim 5 wherein said null output voltage for the lights reflected offsaid marker element is created by adjusting the reflected intensities ofthe lights.
 7. The method of claim 1 further comprising activating alight of a first color visible exterior to the transfer device when themeasured ratio of reflected intensities is not substantially the same asthe known reflectivity characteristics.
 8. The method of claim 1 furthercomprising: creating signals corresponding to the reflected intensitiesof the lights reflected off the area in the transfer device; filteringout any signals created by reflected ambient light; and comparing thesignals created by said first and second reflected lights to signalscorresponding to the known reflectivity characteristics of theencapsulating material at different wavelengths for said first andsecond lights.